An asteroid-mass black hole would be too small to interact much. It would go straight through the planet, and couldn't possibly capture enough mass to be e.g. captured, but it would register as something like a very high energy cosmic ray.
The Schwarzschild radius of Vesta is 396.1 nm [0]; which means it a black hole with that mass would intersect 6.281 cm^3 [1] of material if it went through the center of the Earth.
I have no idea why it might look like a cosmic ray. The surface gravity would be absolutely insane, so I would naïvely expect something like this look like an earthquake. [2]
[0] http://www.wolframalpha.com/input/?i=event%20Horizon%20radiu...
[1] http://www.wolframalpha.com/input/?i=%28396.1nm%29%5E2%20%2A...
[2] http://www.wolframalpha.com/input/?i=gravity%202.67%C3%9710%...
It would leave a trail of wreckage behind it that, on a micro-scale, would look somewhat similar to that of a super-high-energy cosmic ray. A hole that large is large enough to swallow large numbers of atoms, and wrench the remaining ones out of position; that would look not too different from the damage you'd get if you sat in the way of a particle accelerator, at least very close to the path of the hole.
I'm not sure what would happen to you if one fell straight through you, but I suspect you'd be fine. (Unlike the particle accelerator, there wouldn't be much secondary radiation.)
Don't quote me on that, though. And don't try it at home, either.
If anyone out there does, in fact, manage to try this at home, please send a letter about it to the following address:
P.O. Box 5232, SE-102 45 Stockholm, Sweden
Street address: Sturegatan 14, Stockholm
"Bugorski understood the severity of what had happened, but continued working on the malfunctioning equipment, and initially opted not to tell anyone what had happened."
"The left half of Bugorski's face swelled up beyond recognition and, over the next several days, the skin started to peel, revealing the path that the proton beam (moving near the speed of light) had burned through parts of his face, his bone and the brain tissue underneath.[3] As it was believed that he had received far in excess of a fatal dose of radiation, Bugorski was taken to a clinic in Moscow where the doctors could observe his expected demise. However, Bugorski survived, completed his PhD, and continued working as a particle physicist.[4] There was virtually no damage to his intellectual capacity, but the fatigue of mental work increased markedly.[2] Bugorski completely lost hearing in the left ear, replaced by a form of tinnitus.[5] The left half of his face was paralyzed due to the destruction of nerves.[1] He was able to function well, excepting occasional complex partial seizures and rare tonic-clonic seizures."
Unlike a black hole falling in from deep space, one made on the surface of the Earth will definitely remain inside the planet, making one pass through the core every 42 minutes.
It's a good schema to get all the baggage of Earth out of the novel.
He just says, whoops, earth got eaten, don't worry about Yosemite anymore, now here are some space monks that live in huge bubbled space trees.
Much more fun than having to explain things minutely.
However, the gravitational pull of an asteroid would not be negligible, so I guess it would have a big impact pulling things towards it.
https://www.wolframalpha.com/input/?i=black+hole+horizon+rad...
shows a black hole of mass 1×10^29 kg (which is about 1/20 of one solar mass) has a radius of 148.5 meters which is asteroid size.
https://www.wolframalpha.com/input/?i=gravity+of+1%C3%9710%5...
says at one earth's radius away that it has an escape velocity of 1447.5 km/s (kilometers per second), so yeah I think that will either destroy part of Earth or completely consume it, depending on how fast it's passing though.
For OP's question, whether it's detectable or not, it possibly is if it warps the light from background stars (same effect as https://en.wikipedia.org/wiki/Eddington_experiment).
First, they are big enough to be stable, they don't explosively evaporate in an instant. Second, they are much, much smaller than the large one on the video.