All is still well with the hamstring. Reviewing the log I keep on a spreadsheet in my phone, I think I see now why this may have cropped up. Normally after a competition lifters take 1-2 weeks off after such maximum efforts to recover. I had a gap of a mere 4 days. Another lesson learned. Probably even more important at my age. I don't like making concessions to it, but the body needs what it needs.
Anyway, conditioning with 3 sets of 3 box jumps and medicine ball slams, followed by speed bag, SciFit, heavy bag, all interspersed with some time doing air squats off the Samson blocks at the correct depth to dial in how low the proper depth should feel.