Several providers announced scheduled maintenance last week. UUNET/Worldcom listed 60+ different cities in its maintenance announcement for Tuesday 2/19, and more on Thursday. Abovenet said they would be upgrading some of their routers on Monday 2/18 and Tuesday 2/19. Sprint had a few maintenance items scheduled for Tuesday. It wouldn't surprise me if other providers had also scheduled maintenance for Tuesday morning.
There doesn't seem to much variation in the total BGP announcements, average latency or packet losses, so I don't think it was someone tickling lots of BGP routers.
Thanks to all who responded. It looks very much as if this surge corresponds precisely with one of the above-mentioned maintenance windows (further this deponent sayeth not). If you own enough routers, and tickle enough of them at once, you can cause quite a stir. --jim