Don't worry about the jerks there are tons of them out there. I have a 15 gal nano & no one talks to me either
Personally, if it was me that ran into the arse in PetSmart he would have received some very choice words & depending on my mood...... possibly more.
Besides.......Nano's can be more of a chalange to keep with there small water volume, when things go wrong it can happen really fast.