I have found that if I overtrain I get a slight pain in my scalp above and behind my ear. It's a reliable indicator for me that I need some recovery days. Is this totally bizarre, or does anyone else have a similar indicator of overtraining?

it does sound bizarre. Bizarrre is good though.

Actually, could it be your glasses? That seems about the right spot for the ear piece to hit.

My guess is that my muscles in my neck, face and head get tense when I overtrain and cause the soreness.