Chinchilla weird behavior

[Chincheeeela]

Hi all, I have a male chinchilla, 2 years old.

Don't know if I'm worrying too much or it's normal, but he likes to bite his hammock very aggressively, whenever I approach the cage or open the cage door. He seem to do that for a long period of time. Don't know if it means anything bad??
Would appreciate to have some feedbacks regarding his behavior as I'm a new chinchilla owner!

 

[ChinChild]

I have two boys (a 1 y.o. & a 2 y.o.) and they both do something similar...Gizmo will start biting at this hammock & tugging very hard at times, and Mojo will bite & tug on any accessories that aren't bolted down. I thought it was a reaction to stress at first, but we've had them over a year & they continue to do it (yet they are happy as can be, popcorning around their cage and whatnot). It might just be a personality quirk, or it could be as stress reaction - does your chin display any antisocial behaviors, fur chew, or give any other signs that he might be stressed out?