If you put a pied to a 100% het pied you should have hit. But theres always a chance you just got beat by the odds gods. If you had dropped 8 eggs and all normals i would be pretty convinced it was not a het. But the only way to know for sure is to breed em again. I bred my pied last year to 3 hets and got 4 eggs out of one girl and 7 out of another and 9 out of the third. The one with 4 eggs gave me all hets, the one with 7 gave me 2 pieds and the one with 9 gave me 5 pieds so there is never a gaurantee when messing with recessive genes