Ended up reading rephist.c for awhile.

Seems the up/down time is accumulated with downtime discounted %5 every 12 hours.

So absolute worst-case age-out for 100% downtime would be something like .95 ^ 76 (35.5 days) to get down it to 2%. Since the outage is not as bad as that, the guard flag should show up sooner.

Not interested enough to calculated the exact answer. Will just watch it.