Never experienced this on my road bike before, havent changed anything in my bike set up at all but the last 3 or 4 times i've been out on road rides over about 50 miles then the next couple of days my arms have been stiff and biceps pretty sore

Should i be looking to tweak my riding position a bit (which im reluctant to do because the position im in has been fine for the 10000+ miles ive done since ive had this bike and legs / hips / back are feeling fine!) so would lifting weights or doing press ups or something else help out and build up more strength?