^^^None of your golden puppies ever mouthed pants' legs or hands???
I haven't had a puppy in about 13 years (prefer adult dogs!), but have you done any training with her? When she's getting mouthy, this is a good time to teach her an incompatable behavior - something she can do that keeps her mind and her mouth busy so that it's not possible for her to mouth you. If she mouthes you when you touch her, try giving her a treat every time you touch her - touch with, say, your left hand, and put a treat at her nose at the very same time with your right hand.... she'll be too busy eating the treat to turn around and mouthe you. When you're walking across the room and know she's in the mood to come and get your pants' leg, throw a handfull of treats or her very favorite squeaky toy so that she chases those things instead of you. When you give her a toy, only let her play with it as long as you're playing with it too - so you can play tug or throw it so she can chase it, but don't let her have it to play with by herself. This way the value of the toys goes up and she will play with it longer, keeping her mind and body occupied for longer. If you want something to keep her busy, give her a stuffed kong, chew bone, compressed rawhide (supervising her), etc., these will keep her much more interested and occupied than a regular toy.
When are you starting puppy classes with her?? Obedience/tricks Training also keeps puppies' minds occupied, and as long as she's spending mental energy on appropriate behaviors (like the tricks you teach her), she has that much less mental energy to spend on figuring out how to do something you don't want.