Meself, is happens in Britain, too, more and more. All the time, in fact. I try not to let it irritate me, but once you notice it, you can't help but spot it every time.

Another one is the double "is" in the middle of a sentence, as in: "The thing is, is that they don't realise they're doing it" or "The reason is, is that they treat the first clause as if it were a single word and then follow it with a verb." That's grown up in the last year or two and just won't go away.