Why might blood drawn for a blood draw be bright cherry red? All 3 of my kids drawn this wkend. 2 usual dark red, 1 bright cherry red-usually blackish

Hard to tell. No diagnosis can be made just on the basis of the looks of blood itself. Usually venous blood is darker than arterial as it contains less oxygen, but your kids had venous and not arterial blood drawn. If there was accidental arterial penetration, then cherry colored, bright red blood could be obtained, but that should have been reported if occurred.
Artery was hit. Dr. Conovalcuic is right. Probably an artery was nicked. If the area seems okay now, i would not be concerned.