This is the first time I've had a brand-new, handbuilt wheel, and tonight was the first time I've taken it out. At first, it felt great. Smoothest ride I've ever had, super easy to control- all of that first-ride goodness that makes it feel like the first time.

But then (!!), I picked up the pace.. and it slipped. I felt, maybe it was the cog/lockring, maybe something to do with the hub? I don't know. I pedaled harder, and there was a noticeable forward slip. So. Can you help me?

This is such a simple question, and I'm sure there's and easy fix. Have you experienced this before? What do I do?