Why does my 4 month old granddaughter cry whenever I pick her up?

Sometimes I just have to look at her to set her off. i know it may sound funny but I'm upset as I adore her and she is not like this with anyone else. Sometimes she is fine with me but and even smiles but usually she cries and sounds really annoyed or worse, petrified of me.Its been like this for about 2 months and I am really hoping she will grow out of it. Help! Its quite upsetting.