I think that as many kitties as you have Jen, that another white kitty is living/bumming off of you, and you have so many places to hide, that it hides during the daytime, and comes out at night. He was probably just getting a bite to eat, and you walked in and spooked him, so he had to run past you and find another hiding spot very fast, so that you would think it was actually the real Monte I would be looking VERY CLOSELY for another white kitty in the house

Ps- I will search and search for Hannah. She will not be on top of the dresser, I look 15 times before resuming search, but when I walk back into the bedroom, never fails, she is yawning on top of the dresser, looking at me like " Mom, really, do you have to YELL my name so much, I am right here". lol
Drives me NUTS