Captain in this case was just being cautious.About 15 dodgy burned rivets was about it. As everything continued to operate normally he could have just as well continued to STN where maintenance was avail, but made instead the decision to return GRO for same reason.He was one of 3 strikes in GRO that day;engineering staff seem to feel 800 very prone to strikes,no-one knows why,but it really is.Similar thing in same vicinitya year or so ago resulted in a scorched/jammed alpha vane and false stick-shaker(not surprisingly he came back too!)but most common damage seems to be small holes/burns on skin,knackered rivets and a tell-tale scorch mark on trailing edge of starboard stabiliser,which seems to be the preferred exit point.Did see one last year with interesting little trails of molten metal on a leading edge but that(so far)is about all.There you go,nothing juicy there for the Ryanair-knockers,is there?By the way if you don't want to p*ss off the Catalans you better spell it GIRONA next time.