I recently heard someone mention a "one-year anniversary," which, in the good old days, would have been "first anniversary." This construction seems, to my ears, to be growing in popularity, as is the non-yearly stuff like "six-month anniversary," which seems paradoxical. Does anyone know when or where these usages arose, and whether they are linked?

here's some'at from the NYT (dating from 2010):

nyt

Thank you. I had a hunch that this was not a new phenomenon, just one I've been stubbing my toe on rather frequently. I'll just get stouter shoes.