All right! Yay you!
I noticed the same phenomenon about the difference that last little stretch makes (though due to injuries I could never get up to eight miles, much less ten miles) in effort when I did my weekly long run, back when I was running. Can't run now due to knees and hips, but I have other things I do.
And I heartily endorse avoiding hypertension meds if you can. My DH's meds went whacko on him this summer, and damn near stopped his heart. A very scary moment when that happened.