I think my training the past two months to increase my pace helped me this morning. During my training runs, I ran 10 minute miles when I felt good and 11 to 11:30 miles when I didn't feel quite so good (those times don't include walking breaks). Today was one of my not quite so good days, and I ran faster than I've been doing in my better training runs.
I'm going to continue working on a faster pace during the summer to allow my body to better adjust to the increased speed, and I'll decide in the Fall if I should continue doing that or if I should cap my pace and slowly lengthen my distance back to the 30 - 33 miles per week I was running before the half-marathon in April. It will be a significant challenge for me to run my faster pace over a half-marathon distance. Meeting that challenge is a great motivation for me! To give me numbers to aim for, I've reduced my goal-paces by 30 seconds.