From searching, I've learned that Servo getting a human facemask is a random bug that has no obvious trigger, but all of my searches are turning up results from '06. Am I missing a thread in which a solution to this issue was discovered and shared? My Servo has been in formalwear since his activation, but after patching FreeTime (I decided to grab the patch from the UK website since I've never made custom clothing) he now has a female facemask, complete with lovely eyeliner and black lipstick.
I think I'm going to start making my Servos look like humans anyway, so it's not a big deal if there is no solution. It would be great if there is a known solution for this, though.
In case someone views this who hasn't heard of this issue and wants to see what it looks like, here's a picture: