Yes chewing on things can be a sign of anxiety.
When you're stressed out and suffering from anxiety the chewing on things can help you calm down and become less anxious.
Just like a toddler or baby who sucks on a pacifier the pacifier helps them calm down when stressed out or anxious as well.
I used to chew on pencils, erasers, my shirt etc when I was a kid and suffering from anxiety and being stressed out.
Even now I sometimes chew on pencil erasers as well when stressed.
Some kids chew on shirts, rags, their hair, their fingernails etc and even adults do the same thing which is normal.
Some people also need to have something in their mouth and so they chew on things.