Am I missing something about the devil room mechanics?

I've just watched one of NL's episodes and I don't understand how the devil deal worked for him (it's this episode: https://www.youtube.com/watch?v=W9d7klyiOak).

He went through cellar XL and got a devil deal at the end of it. Then he used forget me now, without taking any red heart damage, and completed cellar I, basement II and catacombs I without seeing a devil deal. Shouldn't he had 100% chance on catacombs I, having gone through 2 floors without seeing one? Does the first floor, even if rerolled after the second, not count for a devil deal?