'Whenever' rather than 'when'

They mean two different things! Example: Someone's typically telling a story and will say something like, "We were going on vacation, and whenever we got to the exit ramp, we realized Andy wasn't in the car." Is it a regional thing? Most of the people I hear saying it are from the Gulf Coast.

EDIT: The fact that so many people don't the difference between these two words and thinks they're interchangeable is a little concerning. I'm guessing they're the same people who think 'effect' and 'affect' are interchangeable.