My guess would be from latching and unlatching the door(s). I know my Oslo has a slight "soft foot" and rocks ever so slightly if I have to push to latch the front load door. I would guess that this slight rocking can induce the stove to walk? I need to get some shims and make certain I have it perfectly leveled. My problem is that my SS liner has settled in the past year since installing it, and now I have to pull the stove and cut it shorter. I had a positive 1/4" per foot slope from the stove to the T, now it is almost 1/4":12 the opposite direction. Uggh!