I wonder if that person who poured gasoline on the walkers pit is the same person who drove the trailer into the prison area and got out when releasing the walkers in the back? We never found out who was driving that trailer.
It looked to me like the driver of the trailer full of walkers that the Governor dumped at the prison was a woman. On the other hand, they are hinting very heavily that the saboteur (who set the walkers in the pit on fire) is Milton. I’m pretty sure they are two different people.
If you think back, the person who got out of the walker truck was small and curvy---likely a woman. IMO, Milton gave himself away as the walker burner. When the governor grinningly told him he knew who did it, Milton dropped his eyes and walked away. Dude needs to learn some guile....