On my 97 1.5l I noticed brake fluid leaking from the rear left drum. I pulled the drum to find it FULL of black grease all over everything, shoe pads, drum lining, etc. Right side was fine. What could have caused this?

Are the hub seals known to give out and splurge grease all over? Maybe on a solid rear truck, but I couldn't imagine this small of a bearing holding that much grease.