Do rosy boa bellies change color when stressed?

[FlagonFly]

So during my recent trip to the vet, I noticed something funny while he was being handled. Maybe it was the bright lights in the examination room, but the belly looked very rosy colored. Before that time the belly always appeared to be very light yellow / white-ish color.

I haven't looked again closely since home yesterday as I want to let him chill out after some vet manhandling.

Do these boas (or any other breeds for that matter) ever color change when stress/excited/etc? Like how humans blush? I could swear I looked all over my rosy for actual rosy colors after reading where the name comes from, but never saw anything but black and tan until yesterday. Am I crazy or just haven't seen in the same bright light before?