I was driving right beside the school bus when the school bus stopped and started flushing, which I could see only the front right hand side light flashing. I stopped and looked at the school bus driver. She moved her right hand forward which I realized she signaled me to go, but when I passed the bus, I saw all lights are flashing means I passed a flashing school bus. One car behind me was honking what I thought because I stoppped suddenly. I might get a ticket by mail. Is there any remedy or anything I can do in adavnce?

That's an odd one. Technically, because you passed a school bus with its lights flashing, you theoretically could be charged. However, if the bus driver was clearly waving you past, I wouldn't worry about it. As far as anything in advance: No. Don't say or do anything. All you can do now is wait.