JK... with the proliferation of phones, PDA's, digital camera cases, and the like that people hang on their belt, most (read "reasonable") people are oblivious to a slight bulge under a t-shirt. I have been carrying a 1911 or a Sig in an IWB under a t-shirt for 10+ years and have never been openly "made". I'm sure that another gunny has probably taken note and assumed that I was carrying, but I have never been approached about it.
Look around....the world is full of "sheep". Just watch 'em for a while....most people go about their business without giving a second thought to what is going on around them.