I don't feed blood worms, no one sells them around me and freeze dried is just so messy! I don't have crypts either!
You guys all have great ideas though!
I'm glad to know I'm not the only one, for whatever reason..
Next time it happens, I'll have to test my palms for redness.
I don't think it's the position of my arm, it happens in all my tanks, big or small.