I've been bitten MANY times, lol
The worst case was my 'teaching' rat, Brillo... my lovely old Brillo. Who is now a heart rat, and VERY old....
He bit me once, hit the bone, and I had to go to the hospital. My finger bruised, and swelled to the point I could bend it. I was sent for xrays to make sure it wasn't broken, and they offered to stitch it, but I declined, lol.
I was put on abs, just incase. The doc himself had rats as pets, and I explained that I was taking in rescues, that this one had been neglected, and stoooopid me got in the middle of a rat fight...
If you're concerned, i'd suggest at the least a doc visit.