Sounds like buildup, if you haven't had problems prior to this. Like auntnett says, try scrubbing your scalp more vigorously, or use a low-sulfate shampoo periodically.
As far as the rest of the thread goes, I have dry scalp/sebhorreic dermatitis, and someone recommended jojoba oil here on the boards. It's awesome! I put a little on my fingers and apply it to my scalp in the hairline. It's really helping with the dryness and flaking.