Crystallized Honey IN CELLS!

yes...this happened to me.  While I was extracting this season - we came across some frames (~6 or so?) that had CRYSTALLIZED honey in them.  Nearest I can figure, the bees got into SOME (mystery) nectar source that crystallized on them.  It was interesting and not at all harmful to the batch - because even if some crystals escaped the cell in the extractor - they were filtered out in the final batch......I just wonder what FLOWER/source they got into?!