Male cat biting pillow while kneading and purring,normal behavior?

I’m currently cat-sitting my friend’s male cat and noticed a behavior I haven’t really seen before.

He suddenly went to a pillow, started biting it, kneading it, and purring really loudly at the same time. My own cat (female) kneads and purrs too, but she has never bitten anything while doing it.

This cat seems to always need something to bite while kneading like a pillow or blanket and then he just keeps kneading and purring.

Is this normal behavior for some cats? Should I be concerned about it, or is it just a comfort thing?For context: he seems relaxed and happy when doing it.

Curious if anyone else’s cat does this!