4 month old puppy reacts badly to being petted

Hi!! My puppy will be 4 months in exactly a week and while I’ve been working on handling with her and she does amazing at the groomers (only had 1 appointment so far but they said she was great).. she still would whip her head and mouth me if I try petting her back sometimes and especially her head and neck area so I’m avoiding it.. was wondering anyone else experience the same issue