Reaching for the mesh? like to climb on the top of the cage?
I am not really sure why she would do this unless, maybe, you have the cage roo low. Chams like to be higher up, so they can look down at us. If she can't climb in her cage and be higher than your head, she might think climbing on the top of the cage will get her to a higher place.
My adult chams don't try to climb the tops of their cages. I think as they age and get heavier they lose interest. I think young chams do it because they like to explore.