Yeah, I am quite certain. I hear it occasionally and also I've seen it in writing. Just to back me up, although I am not advocating the usage, here's a few google search results in books.Are you certain that you haven't heard, e.g. "He is in his fifties." ?
John is in his fifties.
The train is in the tunnel.
John is well into his fifties.
The train is well into the tunnel.