I would think that considering everything going on in the region that they probably have many drones in constant operation, simply making a coincidence more likely.

Edit: But I don't think they've released nearly enough information for us to make a good guess; for example, knowing the flight trajectories is important, did this drone shadow the US one, or were they just in the same area?

Also implies a certain level of sophistication, since it was able to track the drone. It seems unlikely to have been radar, but perhaps an ability to follow radio signal?

extremely likely. it was an attack with 1 drone right? normally they would send a swarm

IRGC advisors no doubt.