The bus was well into the no-passing zone before starting to pass. The only reason the bus was able to complete the pass safely is because the on-coming traffic saw it and slowed down long enough for it to do so.
Thank you all for your responses. I did not expect for them to all be in agreement, but I did want to know that I wasn't the only one thinking this was a situation that required some action on my part. I did call the bus company and reported what I saw. The lady I talked to was very nice. I told her that I was not trying to cause trouble, but felt that it was an unsafe situation. She told me that they rely on the public to let them know how their drivers are driving. Their first priority is the safety of the children they transport.
Right or wrong, I feel better. I agree with the poster who said that ultimately, the driver is responsible for his actions.