I've kept pet rats and pet ball pythons in the same room my entire life (growing up I always had both) - in the stores as well the rats are, by necessity, in the same building/room as the snakes. While yes, to a certain extent I am sure they get accustomed to the smell, they also know as soon as a rodent is dropped into the cage with them. Smell is just one cue for a feeding response, they also get triggered by sight and heat.

I wouldn't stress too much.

-Jen