Fiberglass steps blistering/cracking...

Fort Wayne, steel wall, vinyl liner pool w/ fiberglass step insert at shallow end...installed in 1998.

Seems that I have been noticing more blisters in these steps over the past 2-3 years. We also have some small, hairline (non-leaking) surface cracks as well. Eventually I would guess the cracks could leak and am curious to know if there is any fix? As for the blisters, what's the deal with these? Why do they occur? I'm thinking they could also cause problems down the road...

Aside from an apparent invasion of LOUD chirping little frogs/toads this year, the steps appear as if they will be my prime aquatic concern this year. The warm spring did make for some interesting startup issues but nothing lotsa bleach didn't fix quickly...