Sue,

Do you have any water rinses in your staining protocol?  OCT is water soluble and dissolves best in water.  I get leftover OCT on my stained H&E slides (frozens) if I don't rinse thouroughly in water.  Also, we used to fix the frozen section slides in 100% reagent alcohol but recently switched to a fixative that has some water in it.  This fixation step not only gives better nuclear detail but also gets rid of a lot of the OCT.

Laurie Colbert