Todd he said his shoulder not elbow. I had to do a double read myself.
Scott,
Hitting your shirt sleeve happens to many if it's loose, but if your hitting your bowarm "shoulder", sounds like to are over extending you bowarm out so far your pushing you shoulder into the line of your draw and maybe the bow may be too heavey causing you to push out that far.
Bow arm should be slightly bent and bow canted (on an angle say for right handed at say about 10 O'clock) where hitting your shoulder should never happen. Would love to have ta post a picture.