Dumb mistake but I did some back to back hard running, felt a problem that I thought I could run through, then wham! Attempting a long run the day following a 2 mile time trial, my hamstring starting telling me to back off!
I gimped home last Sunday and haven't run since. I'll call this a first degree strain that needs rest.
Thankfully, cycling does not seem to be a problem. I'll give it some time until discomfort goes away before I resume jogging, and in the meantime this gives me some time to swim and ramp up some miles on the bike.
Then it will be time to get strong!