Did the president just fly by my window?

If the white-topped chopper was smaller, it probably wasn't the president. Marine One usually flies in formation with same-sized choppers with green roofs - and rarely flies last in formation - all this according to my observations of five years in an Arlington office building (9th floor) right next to I-395, which is also one of the routes to and from the Pentagon and downtown DC.

Boy am I glad not to work there anymore. Less distraction by air traffic at office window level, now.

BTW: according to the White House Mr. Bush was in Washington a little more than an hour after your helicopter sighting. Sorry to spoil your idea.

Wow, such a fantastic comment inspires and does not spoil anything. Thank you, this is great, please write more comments!
We live on the Upper Westside, so all the choppers that fly by here seem to be heading up the Hudson river, which would probably mean that they are going to Connecticut or more likely Albany.
I hope that I was not seeing things, so maybe Marine One has a smaller sister and she was going to relax upstate? Or maybe Governor Pataki had borrowed the machine and took it home to show to friends and family? : )

You definitely weren't seeing things - for the use of high-ranking officials (probably generals and up), there's an entire fleet of nicely finished helicopters with white roofs, coming in a range of sizes to accomodate the various degrees of importance.

Things you learn in Washington, DC.