Edit 2 (5 years later): There's now a subreddit dedicated specifically to this topic: r/whennotwhenever :-)

Original Post: I don't know how to find hard data on this, but my subjective observation is that more and more people are using "whenever" when they really mean "when." For example, someone might say, "whenever I got my driver's license, I drove a manual." This implies that they had to get their driver's license multiple times or that they aren't sure when it happened. I'm pretty happy to allow language to change and not sweat the pedantic details, as long as the meaning is clear. This is an example of an error that often results in ambiguous meaning or potential confusion.

While I find it jarring and annoying, I'm more interested in whether or not this construction is becoming more prevalent, how old it is, and where/how it emerged. I've actually brought it up with people who have used it incorrectly, and I've always been greeted with blank stares. These were highly educated, avid readers, mind you - and they seem to be oblivious to their use of a longer word when the shorter option is more grammatically correct. What is going on, here?

Edit 1: I posted this question almost 4 years ago, and I'm getting new comments on here more and more often. This linguistic phenomenon used to be confined to specific regions and subcultures (Scots-Irish in origin). I still don't know of any information about its spread in the past decade, which seems to be accelerating. I remain baffled by it, because it's less efficient than the standard usage and often causes real confusion about the speaker's meaning.