Hello Bunny world!

I have a question about my buns behavior.
She has lately taken to chewing on her cage. Now, I understand that this could be boredom or simply wanting to come out, however, her two level cage has two doors, which are always open and they are open to her own bedroom, which is filled with bunny castles, mazes, boxes to jump up on tunnels of different sizes and textures, handmade toys(bags and paper towel roles with hay and treats, foraging toys, etc), store bought toys etc. I change the toys around regularily and am always changing her environment around so she feels like she has new places to explore. Twice a day the baby gate comes down and she has access to the house for 1-4 hours a  day, and she will sometimes come out to explore and sometimes not.
She is a spayed female, approx a a year and a half.
I have posted a picture below of her chewing on the bars, she will do this even if I petting her, trying to block her nose.. etc. Almost in a trance about it. She will do it for a few seconds to a few minutes at a time.
SO, my question is,, is this typical of bunnies who are bored? lonely? playing? trying to shorten teeth? mental issues? IF any of the above, suggestions would be appreciated!
As a side note, eating, pooping, drinking all seem pretty normal.