Originally Posted by
Worldsong
I'd say that Occam's Razor agrees.
I'd bet a lot of quatloos that if you don't disarm the trap like Haley did you won't even notice crossing it. It's not the kind of trap that detonates or betrays its presence.
Instead the difference in floor colours makes it extremely likely that if you manage to bypass this trap you're entering a different pathway than if you trigger the trap. Granted I doubt a high level rogue would leave it at that so they'll need to remain careful, but odds say that this is the first step you need to take to reach the Gate.