hmm...I think, as u did active external rotation only 10 degrees on 3rd post op week and it was pain free so there is almost no chance to tear the labrum again because ist 10 degrees from the nutral position will not generate any significant pressure on the ant. structures to the head of hum and specially if its been three weeks gone.
usually after 4th week pt. can start active external roation in painfree rang and that is almost ist 10 to 15 degrees.
gud luck