Awww! I love your kitty names (huge HP fan here!)
I'd say it could be teething and it could be the kitten "suckling" reflex. If it's the suckling reflex, she's seeing you as a mother figure and it makes her happy to mimick what she would do on her mother's teet on your finger. 5 weeks is young for a kitten to be away from her mommy (if she is indeed away from her mommy) and being weaned too soon could mean she'll do this suckling thing her whole life. I once had a cat that loves to do it on your t-shirt. Got drool everywhere!
If it's teething get her some rubber toys to chew on (I'd do this anyway just in case haha). My cat loved cardboard boxes for some reason :shrug:
A third otopin is that your cat just likes do ing this haha. I've also come across this in an older cat I adopted. When I patted her, she would instead want to lick and lightly knaw on my figers. Can't figure that one out.
Then she won't develop an "it's okay to chew on mommy" habit haha. Wouldn't want that when she has her adult teeth eh?
Good luck with Herm-ohn-ninny!