I suspect this is a situation where there were indeed 2 lanes available and the OP swung wide partially into the left lane to ensure a clear right hand turn. We have all done it. I did it recently and someone coming from behind went by me on the left (into oncoming traffic) and was honking at me all the way. You cannot avoid stupid and you have to assume stupid is going to happen. If you leave your lane (no matter the intention or signal) you better be sure you can safely return to that lane or make that turn.
