You don't mention if they're usually the same pair she goes for, but the shape of the handles and the upright position may be a factor in relief. In any event, I think some small amount concern is warranted since many tooth and gum issues are not directly visible and so it may be that she is experiencing discomfort that is alleviated by the activity (similar to baby teething relief).

Another way to check on this is try rubbing her jaw a bit and see if she leans into it much more directly than you would expect. One of our cats definitely has issues below the gum line and responds with clear relief when we rub her jaw area. She leans into this very hard, much more so than other types of petting. Unfortunately, because of a heart condition, they can't put her under to fix it.

It could be nothing, though, just a odd behavior, but only a vet can really confirm that.