pimples on bodyparts I trained hard

I did some incline bench after neglecting upper chest for a while. Next day I'm sore as a mf in my front delts and pecs. But I also noticed some pimples in that area.

Same thing happened after not training calves for a while or blasting my biceps like never before.

I'm a 40 year old man, I normally never have pimples anywhere.

Not looking for a way to reduce pimples, I don't care, just wondering how this happens. Does it say anything about testosterone levels?