Originally Posted by san~man
It's not their responsibility to give cars behind them a "heads up," it's the responsibility of the driver in the back to keep a safe distance.
How do you know that they weren't caught off guard like yourself, and executing an "emergency" lane change in order to avoid an accident?
Put the responsibility on yourself instead of someone else.
It's may not be there responsibility but it is recommended by DMV as a safe drving practice to warn traffic behind you.
They could have been caught off guard also, but just hard for me to believe with them sitting so high they can't see many cars ahead.
My original question is if this ever happend to anyone. I'll take the answer as NO. And from everyone's response, I guess I am the irresponsible one for complaining.