yea, that really wouldn't make any sense.. they could have let him be poisoned, they could have shot him back at the pool.. why wait till then?
plus, it doesn't look like he was aiming or even looking at jesse, he just started to bring the gun up and was looking forward as if to make sure he was clear to get in the car and start driving -- maybe he was even covering for jesse to hurry up and get around to the other side
jesse was off to the left a little, and mike's eyes weren't on him
that's my take