I used to be one aswell until 6months ago.
I used to cop a bit of stick from fellow employers for thinking alot about the weights of gear. Most of them (its worse in Aus, and its complicated over here) are unaware of ultralighting.
There was a guy that came into the store alot, that we dubbed "Golite man" (he was always wearing UL clothing and gear in the middle of the city). He would come in often and ask random questions about new gear on the market (most of it US gear) and whether we were getting it in or not, and generally waste alot of staff time. He never bought anything from the store, we knew it, and it was really annoying. He knew that we would never stock it, and that in Australia we only get a handful of the ranges of most US gear manufacturers from our suppliers.
I really enjoy helping customers and often used to get letters sent to the store thanking me for service, but this guy did annoy me. I dont mind people that come in and use half an hour or so of my time and then dont buy anything...they need help and its my job to give them the best advice possible...even if it means they go to another store to find something that works for them properly. This guy though knew his gear, and with the items he often talked about, probably better than me.
Most ultralighters know alot more about the intracacies of gear than gear store employees. Its a fact of life-we are gear freaks to the extreme. If you know about a piece of gear and don't need any help, then let staff know straight away when they approach you and don't drag out conversation where you establish really nothing other than the fact that they aren't "UL".
This may be what that store employee has experienced in the past with "Ultralighters". It's quite possible he wasn't annoyed with you at all.
But I don't miss "golite man" since I stopped working there. Thankfully(???), he is probably the only ultralighter in Adelaide, South Australia, apart from me.