Mean biting pissy mice?

Okay, for my BP, I've been going to the store and buying 3 adult feeder mice at a time, every 3-4 weeks. I get home usually feed one immediately which is readily gobbled down. Monty is a very easy feeder thankfully. And then the remaining 2 mice I stick in a plastic pet cage to be fed over the next couple weeks.

Well I've never once had a problem with mice getting along, until today...

Today's new batch is a kind of smallish adult and a full sized adult both females. And the big one, man, she is mean. she bloody bit my finger, and shes been fighting the smaller mouse. I'm gonna have to stick her into the box I got them in to await her execution date, don't want her to kill the other mouse.

Is this common? Ive had others try to bite me before. But never seen em try to kill each other. Thoughts?

I've yet to have a feeder mouse try to bite me, i'd go and feed that one off asap unless your snake is really that full...


edit: don't want to mislead you, I've only dealt with maybe 25-30 live feeder mice in my life.

A lot of my "pet store" quality mice I notice go through a nippy stage right around 4 weeks, where they will nip and bite you when you scare them. By 6 weeks+ they have usually grown out of it. *shrug*

Idk how big yours is?