Just had a breast reduction. one of the incisions has what appears to be a small pocket of blood trapped under the skin. should i be concerned?

Bruise VS Hematoma: You did not provide a picture, but this could be a bruise or a hematoma. The latter situation might require evacuation/drainage. You should see your surgeon and point out the area of concern.

Concern see surgeon!: Your surgeon should evaluate this at your soonest opportunity, in person, it could be, but they must be personally and directly involved. This is something that they will want to know about.

Talk to your doctor: Surgical risks are both general, and specific to you. Talk to your surgeon.

C Surgeon.: Best to be seen by your plastic surgeon who is in the best position to advise/treat any complication. Best wishes.

Probably nothing: At least send your doc a picture to be sure ok.

wound issue: With any postoperative wound issue it is best to return to the primary surgeon as dr. Pousti has indicated. Your particular problem may not be significant however if it is your plastic surgeon will be the one to determine that.