Man, I saw that thing moving sideways right after liftoff and I thought it was a gonner! Huge congrats to SpaceX for landing with an offset engine like that on their first try!!!
The amount of kick to the side is almost certainly due to the offset engine, but they would definitely design the flight path (with that in mind) to clear the pad as fast as reasonable as well.
From what i remeber some Soviet rockets had after a string of pad destroing failures any abort commands disablee for the first 30 seconds of flight - regardless of what happens, it must not hit the pad, or Barmin (the chief designer of most Soviet launch complexes) will be angry and you don't want that.
They are only using one engine this test, but are testing the flight-design thrust puck (as opposed to some interim structure with a centre mount for the single engine).
This test article uses the same layout for engines, but with one engine instead of three. So that one engine is offset from the center.
Their flight software is already capable of handling the multiple engine out-scenario and compensating for it, so there's no real reason for them to center the engine for the test article.