Is this a rapid change?

That emblem of standard English, Radio 4, is worrying me (again). The word "estimate" is pronounced to rhyme with "mutt" not "mate" when it's a verb. "Contribute" and "distribute" are pronounced with the emphasis on the first syllable: I was always taught to stress the second, and I think I still do.

The actual change is not much of a worry. It was always a bit daft to say conTRIbute but contriBUtion, but then how much better is CONtribute and contriBUtion? The speed of the change is surprising, however. Either I haven't been listening properly, or this has happened in about five years.