NaOH is somewhat souble in DCM, so there definiteley was some in your final DCM layer, before you evaporated it or crystallized it. Next time, if there is one, get yourself a seperatory funnel.....once you collected your final DCM layer with the goodies in it, put it in the sep funnel, wash it with an equal volume of water, then about a 10% solution of Sodium Bicarbonate, equal volume as well, twice this time, then once again with water. This procedure should effectively neutralize any and all NaOH left over in your DCM layer....now proceed as normal.