That's definitely no feeding response, lol. I get a few of those every season.
In my experience, they are frequently difficult starters. They see everything as a threat, including the mouse or rat they're offered. I've seen one of those little nippers get SO upset, it bit that poor rat pup 15 times, and was so wound up it looked like a little spring, hissing like mad. Not remotely interested in eating it, lol.
I have had to assist-start at least two of this type.
On a more positive note, I had at least one of them around long enough to see it grow out of that behavior and actually become handleable.