I've now run 4 days of completely pain-free running!!! It's fantastic.
So I took most of last week off, then saw the physical therapist on Monday. It was a different guy this time, and he seemed to have the magic touch. We spent the entire hour working on loosening up my hamstring and quads... and I ran that night without a problem. So moral of the story: Spend a little more time on my stretches. I'm loving it.