Is my doorknob handleset installed correctly?
There is always a little difference where the strike catches and the deadbolt hits the edge of the keeper. If there wasn't, the deadbolt would be difficult to latch. The weatherstripping needs to be compressed when the latch sets into the strike allowing the room needed to let the deadbolt engage easily. When the latch is depressed, and the door releases the little bit that it does, the weatherstripping should still be compressed enough to do its job. 

FWIW, the odds of a limb hitting the thumb latch and creating a problem by doing so is very improbable, in my opinion.