Telephone weirdness

I'm a bit shocked, when a friend from school calls me Sunday. My phone wasn't with me, so my 5 year old niece picked it up, she hands me the phone and I tell my friend who she spoke to earlier...

"Oh, I thought that was you." My friend says.
"No, no, that's my 5 year old niece." I reply.
"She doesn't talk like a little girl."

This is the third person who has told me this.