Leather covering on my ear cushion is peeling off--do I replace it?

I’ve been having a slight problem lately where the leather covering the foam on the ear cushion is starting to peel out. I used to be able to wedge it back into place with my fingernail, but I think I’ll probably have to find a more permanent answer soon. Can I just glue it back into place, or is that bad for the earphones? Should I replace the whole ear pad?

Also, would the answer be different if it was just a Solo rather than Solo2? The headphones are actually Solo, but not the HD version or anything. I don’t think there’s really a huge difference between the two.