Guinea pig ate a little bit of felt?

I recently got a guinea pig and I made him a tunnel from felt that so he could use it until I got a real tunnel. I found out that he chewed off a part. Its not a lot but I'm so worried. He does seem to eat a lot less than before. I gave him some pellets in the morning and he didn't eat it all until about 3am which is very unlike him. The size of the felt he chewed off is a little bit smaller than an eraser. Do I have to take him to the vet? Is he going to be ok?