Yet another new PB, but am I overdoing it?

Distance: 1 mile
Time: 7m23s

We had a power cut at work today. The whole estate was without power from about 10am. Shortly after midday I went out for my run, and got round in a whopping 8mph. That's twice as fast as walking pace. Upon my return to the office, I was glad to be told that I'd made the best use of the wasted time that the enforced blackout had had everyone else sitting about doing not much for the 2½ hours before we were sent home.

However, my leg now feels a bit sore, so I can't help thinking that I've pushed myself a bit too far unnecessarily. It'll be a good acheivement to break the 7-minute-mile, but I'm not in a rush to get there. So tomorrow I rest my leg from running, and adopt a gentler pace again at the weekend.