New pup ?s - scratching, biting self

[dsmcculley]

We just brought Sasha home yesterday...much earlier than we anticipated, but that is another story! She is just over 5 weeks old. Our first night was wonderful. She has really surprised us with how easily she is adapting to us and her new environment. Everything is going smoothly. I have just noticed that she scratches herself around her collar a lot...at least a few times during her play time and a few times when she is outside pottying. She is also biting at her hind legs/groin area. She's not licking as if cleaning herself, but nibbling like she is scratching. Is this normal baby behavior...or could she have fleas or be allergic to her collar? Her collar is the standard nylon collar (Lupine). The breeder preventatively treated her for fleas a few days ago.
Maybe I'm just over concerned about my baby.