Was it incline? I had a similar instance where I brought the bar too close to my chest on incline after years of always flat benching with safety bars only reaching up to 1-2" from my chest and I believe it was due to overstretching.
It has taken about 3 weeks to feel better but I still feel it when benching very lightly. I am guessing it may take about 2 months to fully heal. I would keep the bench presses down in weight and work your way back up in 2-4 weeks to feel for the discomfort and hope it is all gone.