Surprise! You ran kind of fast!

I planned to run a 10 mile progression to bounce back from the last few miles of the long run.
I was amending a Woodley 8 to become a Woodley 10, but somewhere in the presdiential streets, I lost my way. I wound up on Arlington Highway and had to adjust. I noticed my right quad was rather sore, and I was pretty bummed to find most of the roads still slippery with loose snow. This is where I ended up going.
When I calculated my pace for the run, it turned out I wasn't as slow as I expected- rather, I ran 6:30 pace for 11.2. Not bad, even though it wasn't what I had planned.