I had a strange incident today on my way to work involving a school bus

Driving in a 40-50 kmph zone, cant remember exact.
I was driving north on a 2 lane street at the speed limit, on the left lane but 1-2 car lengths behind a school-bus, which was on the right lane.

The bus turned on its flashing lights as it was slowing down to stop.
By the time i noticed it, i was already approaching the rear end of the bus.
So i continued on, as i passed by, the bus was coming to its full stop.

When I drove by the driver did not honk or anything.
I looked in my rear mirror to see it fully stop and pull out the stop sign arm.

Then, in my rear view watched an SUV pull around from behind it and illegally pass it while it fully had its stop sign out, from what I could tell.
(Which was kinda strange to see, as I was just being worried for myself at the time)

As I waited to make a left the bus came to the intersection, but stopped a couple lengths back, as to write down a plate. Maybe mine, or the other persons. (If what I saw was correct)

There was no ticket issued, as there was no cop.
But If I do receive a fine in the mail, can I fight this/get it reduced?
and if a fine was to be mailed, does anyone know how long it would take to come?
Should I be worried?