LOL Serena, I did that too with my BIL! "Thanks sweetie!" I said to him. My SIL was not around, but my kids thought it was hysterical! He sure shot me a look, but we all had a good laugh.
BTW, I am laughing about the posts saying that the use of these kinds of endearments to strangers is a southern thing. I'm from the Bronx originally, maybe I'm a southerner at heart!
My BIL, also from the Bronx, always says "Yo!" to get someone's attention. I always cringe! I think I prefer hun and sweetie!