320 at 10 weeks isn't bad at all! That is quite normal.
Haha, vets love to do that... my vet is awesome with the health side of things for hedgies but is not as familiar with care and what is normal and not (or moreso, used to the fact that there is such a wide range of "normal") for weights. When I told her that I was trying to get Inky to gain weight a year ago (he was 270 grams at 2 years old) she got concerned and said that it was a bad idea because obesity was a real problem in hedgehogs. I laughed to myself, because I know Inky will never be overweight. It's a struggle to only maintain his weight, let alone gain. You just have to know what's healthy for your hedgie and hope that the vet realizes you have a great experienced community backing you for these aspects of care. Since most vets aren't familiar with the up-to-date care that educated communities are providing, it's best to help educate them from your point of view and let them help with the treatment of problems only. That's just my opinion.
If someone out there has a vet that is very familiar with proper hedgehog care, you are lucky! They are one in a very small number.
