I recently started a third job at a supermarket, do people think i'm retarded?

my problem is i do not like talking to the type of people who work there, as they are overly talkative and just Gabbering mindlessly all the time on meaningless things like the price of gs and the weather. i just get carts and bag grocerys, so that is why i am not required to talk much of the time. this is also a job a retarded person could do. the reason for my question is one time when i was bagging grocery's, two coworkers whispered to each other directly in front of me, and another time a clerk talked to me the way you would a child(very calm, slow, falsely interested and positive). i used to work construction and am finding the extreme differences of personality between us and retail employees amazing. i want to come off as a nice guy who blends in, not a retard. do they really think i'm retarded because i don't spark up conversations about produce and the struggle of everyday life in the supermarket?