You can make changes to maps while doing a test-run? No, wait, what probably happened is that you noticed something off, saved, quit test-play, modified the map, fired up test-play again, loaded the game, left said map, came back, and the map corrected itself. Or something like that?
Regardless of the case, I fail to see how such would be a glitch in regards to the end-user (aka: a player of your game), given that the end-user is (presumably) not going to make changes to your game.