personally I think it is inappropriate for anybody to do, but I understand that this is accepted as pretty 'normal' behaviour. Perhaps you should have been concentrating on getting the number.
Totally agree with the watcher it's inappropriate and reduces you to the level of the bus driver.
If you can remember the company they will be able to trace which route and the driver, but try to refrain from the gestures in the future and it shows you're the better person.
Hmm i am divided. Yes and no. No i dont think you should have really...but Yes i wouldve done if it were me.
I nearly got out a lectured some woman this morning on how to drive/rules of the road as she clearly didnt know!! idiots on the road annoy me..A LOT! haha
It may show you're the better person but it does make you feel better I'm afraid !
(I have pefected the w...... sign but I never use the two fingered one.)