That does sound a bit concerning. Part of me thinks it sounds like they really do know you wear a system and just haven't brought it up to you before and have kept it to themselves. On the other hand, on a windy day I was with some girls and my best friend said, "man i hate the wind!" while he was adjusting his windblown hair and one of the girls said, "ya that's just cuz you wear a toupee." I know for a hard fact my best friend doesn't wear, so she really did mean it as a joke....