my cat eats plastic?

It's amazing after reading this newsgroup for a few weeks how much knowledge
is out there when odd situations arise. I dont know if anyone has had this
happen before, but my cat Gabe loves to eat plastic. Not all kinds of
plastic, but he is extremely partial to plastic grocery bag handles, or
stray pieces of a ripped open bag that sticks out or that fell on the floor.
Its as though his kitty cat nose sniffs out plastic within his range and he
zooms over to it. He knows he's not supposed to eat it (ie, I hear rustling
and walk into the room and he runs away from the bag, looking innocent, or
stays there trying to swallow the piece he just ripped off) but he still
does it anyway. And its not just chewing, he actually eats it; I will pry
it out of his mouth if I catch him at it. Sometimes he throws it up,
sometimes it just goes though his system... anyone know what gives? This
seems extremely unusual! I just accepted it as part of him, but I thought
maybe someone had some knowledge on the subject...