After breaking my incline bench PR two days ago, I got some aching in the lower back of my left deltoid, right over the back of the pit on the shoulder. I was surprised by the progress. Went from 120 x 5 last week to 130 x 10 with ease. The pain is starting to go away now, but it hurt yesterday when raising the arm above parallell. No intense pain, but I hadn't got it before.
It was most likely caused by less than perfect form. I don't think my form's bad, but it I guess it could improve. I've learnt to arch, pull shoulder blades together and stay tight through the whole body. Anyone have any ideas what could cause the aching?