Does anyone else weigh their mice/rats at the store before they buy them?

Everytime I go, I tell them what I'm looking for and they box it up. I'm pretty bad at judging size and weight so I peek at it before I buy it but weigh it when I get home.

The first time, all 5 mice were way smaller than what I wanted. Around 8g. Second time, I tell them a little bigger than last, and they give me bigger. WAY BIGGER! A 46g mouse? She's not "XL" ..she's really fat and when I showed her to the owner of this other pet store that I talk to a lot, he said she was pregnant. Nice. I guess? It's been a week and she's still just.. big.

Anyway, I brought my scale in today and the lady looked at me like I had 3 eyeballs. "Why do you need to weigh them??" Because unlike her and her 2 giant BPs that get fed pinkies, I'd rather something a little more appropriate?!