Just my opinion but, I would talk to the manager/owner to let him/her know of the extreemly unprofessional manner in which you were treated. This guy should have better sense than to walk in front of a weapon in the first place....he was in "condition white" and had no business saying what he did. If there was a "dumbass" in this situation, it was him.
Depending on the outcome, you might want to let everyone know where this happened so others can avoid a similar situation.
That said, when I'm gun shopping, I always point upwards towards a light fixture etc. so that there is never a chance for this to happen.