The eyelid might have a wart. I would not necessarily RUSH to a vet about it, but have it looked out whenever the cat gets checked again.

Heavy cats (and older cats, and yours seems like both) get matted easier because they cannot groom themselves as well as they should. Comb the mats out with a metal shedding comb. Resist cutting them with scissors because it is SUPER easy to cut the skin as well. If necesary have your vet SHAVE them out with a clipper blade (much safer). then the eye could be looked at the same time.