Are you nursing a late season injury?
It always seems that many triathletes end up with end of season injuries after that final A race. Some are just from repetitive motion, others from upping mileage, and some from muscular balances.
During the off season the focus tends to be building for races. Strength training goes by the wayside in the summer when the priority is on racing and as a result imbalances in muscles tend to create problems.