The fiberglass is very stable. Just inspect the paper (if it has the paper backing, sometimes it is just the fiberglass batting), is still in good shape which it should be if it didn't get wet.

Make sure no critters have tunneled into the fiberglass and established their homes (Nests).

Does fiberglass insulation get old? I have had a few rolls of fiberglass insulation sitting in a shed for a couple of years, should this be a problem now that I am ready to use it? (ceiling)