Why would anyone be surprised to see an actor who had been in Star Trek? Do you unconsciously assume Trek actors only do Trek and cannot appear in any other shows? I find the question to be very odd.
I think it's not that we're surprised to see them at all, it's that we're surprised and pleased to see them in other things.
Spot on, Timewalker.
I meant it in the sense of you didn't know they were in a movie/tv show you were watching, and then suddenly you spot a familiar Trek actor and say "Hey, it's that