I can see her just being flat uncomfortable undressing in front of people. It could be self image problems, or just not being comfortable exposing oneself in front of strangers. I do notice kids having body image issues at a very young age, though. For instance, my daughter (8) already doesn't like wearing her coat because she thinks it makes her look fat. I'm like dude! You're 8. You're a kid. Be a kid. I can't believe she's already conscious of these things. Crazy world we live in.
I know what you mean. Before I would say things like I feel fat in something and then I noticed my daughter saying things like that. I quickly changed what I said around her so that she wouldn't see herself as anything other than a healthy kid.