To me, it sounds like the process of micro tears healing. When I first started PE, it there was a lot of itching and some dull pain. Now, the itch, after a workout is almost non-existent, and the red “micro dots” show up less frequently. I do not worry about the red dots, as I understand them to be considered a neutral PI.
My unit usually aches a little on day 2 or 3 of consecutive workout days. I take it as a sign of healing, which in turn, equals growth, I think.
Paraphrased: It is not the critic who counts: The credit belongs to the man in the arena, whose face is marred by dust and sweat and blood, who strives valiantly, who errs and comes up short again and again, who, at the best, knows the triumph of high achievement, and who, at the worst, if he fails, at least he fails while daring greatly, so that his place shall never be with those cold and timid souls who knew neither victory nor defeat.