Are traps randomly rolled when you step on them? I have noticed that when I get teleported, then move back to the same tile, it is a different trap. Not sure if that is intended or a bug with the flag not getting cleared...
Each room is randomly seeded with a monster, treasure, a trap, or will simply be empty. The content, however, is randomly generated only when the player enters the room. My limitations as a programmer didn't allow for anything better than this for now.