HaLeiVi: This has nothing to do with gilgulim, but there are very specific mitzvos that Moshe Rabbeinu didn’t learn about on Har Sinai, and there are very specific reasons for each one (another one is Bnos Tzlofchad, etc.). To the best of my knowledge, everything else was covered.
If it weren’t twenty to eleven at night, I’d dig out my Chumash notes and figure out which mitzvos they were and why, but I don’t think that’s really going to happen.