Ask for it back...don't be rude, just tell them your side of the story. If they deny it or give you crap just leave and don't go back.

As for valvecaps...waste of time. Like mentioned before only time I use it is on my spare tube so the stem doesn't poke me in the back. It's not like a Schrader valve that can easily be pressed and let air out and needs a cap. The screw on cap is built into the stem/valve.