Since it is a sudden new behavior, it may be a good idea getting your kitty checked out by a vet and ask for a blood test to be done. It could be pica, or something else medically going on with him.
One of my cat likes to gnaw on things, but it's usually due to boredom or wanting attention from me. I had to resort to spraying "Bitter Apple" taste deterrent on any cords, plastic bags, window sills, table corners, etc! The difference with mine is that he started doing this when he was teething, and hasn't stopped from kittenhood!
Hope others can help you further, and I hope it's nothing serious but a minor behavior thing he somehow picked up.