You're so tiny

So I'm not a very big person. 5'2 on a good day and 125. I always get the comment about being so small. I feel pretty average for my size. I just don't know how to respond. Do I agree with them or keep laughing it off? At the same time I don't want to be rude. I went to my husband's work today to pick up his check and again I got called tiny. I don't know if people expect me to be tall because my husband is six foot or what. Like why is there a need to comment on my size? If it was the other way around I'm sure no one would bring it up. It just bugs me.