I think you guys are confused as to just what a "Poseur" is. (and yes, "Poser" without the u is also correct, but it just has more meanings attached.
A Poseur is someone who regularly pretends to be something he (or she) is not. It is also someone who affects a particular attribute, attitude or identity in order to impress or influence others.
So basically, if you guys were wearing these shirts to "fit in" or be "cool" but didn't really like Falconer, or had no clue who the heck Falconer was, THEN you would be posers. But you are true fans, every one of you, and you're showing your support for a band you love, AND you could easily back up your fandom, even if you hadn't been to any of these concerts that the shirts are from.
So nope. No posers here. :P