Since the handler told the dog to sit, it would be a controlled break in my book. I would put it in the category of moderate faults that were so slight as to be considered only a minor fault. Based on what was said above, I don't think this would take the dog from first to JAM, but I'd have to see it.
Had something similar happen to me in a Q with my creeper. Every series in both the Am and Q that day the dog crept, but he is not a breaker so I never said anything, but the judges were pretty consistently telling me to re-heel my dog. Last series of the Q in which we were doing very well birds went down, dog crept a couple of feet and stopped. The judges didn't call my number and I *thought* I heard them tell me to re-heel my dog, so I told him to heel. When he was back by my side, they called my number and he nailed the marks. At the placements, we got a JAM and the judges told me that if it were not for our controlled break, we would have gotten a very nice placement. I started to ask "what controlled break" and then it hit me what happened.
I also told my dog to sit once when it head swung in an AM. Judges let me get the birds, but unfortunately they heard me. Oh well, It happens.