I've never had problems before when I used to lift, but recently I've been noticing that my left rotator cuff has been feeling pretty tender.
I've been doing this exercise daily (a few sets of 8 slow reps with a 5-lb. dumbbell), especially before I do my benching/pressing:
The pain/tenderness I feel happens when I am opening my car door, opening a window, lifting a chair away from me, etc. All external motions, which is why I chose to do the external rotation exercise I linked above.
I haven't been noticing it going away though, if anything it has been getting progressively more tender. I'm not really sure what to do. It never feels bad while I'm working out, just while I'm at home doing normal stuff.