I just don't get it??

Anyone else ever dealt with something like this??

Every time I mention her birthday or try to get an idea about what to do for it, this is her reaction. I know I've made comments before that she's my baby and I don't want her to grow up, but seriously??
I've made a lot of comments about many other things too, why is this the one that stuck in her head?

My little sister was in town last weekend and asked her how old she was gonna be at her next birthday and this was her reply, "I'm gonna be 4, but don't worry I'm still gonna be little. Just a little bigger & all my clothes will still fit me. I don't want my clothes to not fit anymore. I don't wanna be as big as you." Aimee was like "thanks!" LOL.

I seriously don't know what kind of phase this is. Has anyone else ever had a kid who went through this phase?? Is she liking the fact that she's getting so much attention from it maybe? Usually kids are thrilled about their birthdays!