Must have been doing a little more then "printing" if he could tell it was a Glock.
The more I thought about it I really think that glock was the only type of gun he knew and he was just trying to sound cool. And t was just a coincidence that i happened to be carrying a glock. Even if my gun had been fully exposed, with the holster i wear and dimly lit bar he would have had to been uncomfortably close to me to know if it was a glock....compared to say an XD.