That shouldn't really be possible. Technically speaking, if it is your turn, you will move next bar nothing. However, if you were using mouse input and moving a few squares, it's entirely possible that it moved into the doorway a turn before you moved there. That is simply an inherent flaw in using mouse input over large distances.
My "favorite" collision was running into a Tunneler and having both a reactor AND my power amp disabled. Soooooooooooo maaaaaaaaaad