I realize that the OP is talking about a 450, but for the sake of future searchers:
I'm on day 4 of the blinking wrench on my 451. It does keep counting up each day. Took it into the smart center today. The service guy told me it is indeed a time function as well as mileage. And if I had it serviced, it would be flashing again in 365 days, or 10,000 miles, whichever comes first.
With 5,000 miles on the clock, and having changed the oil once already, I'm not interested in a $150 10,000 mile service just yet.
I've tried the instructions on evilutions site a half dozen times with no success yet. I was one of the first round of deliveries last January, so I suspect this is going to be a hot topic in the coming weeks, as the lower mileage cars start blinking on a time basis.