Packet from port 80 with spoofed microsoft.com ip

Hi,

I received a packet on my cable modem today, allegedly from microsoft.com:

18:41:35.663374 207.46.249.190.80 > my.cable.modem.ip.1681: S866282571:866282571(0) ack 268566529 win 16384 <mss 1460>

$ host 207.46.249.190
Name: www.domestic.microsoft.com
Address: 207.46.249.190
Aliases: microsoft.com microsoft.net www.us.microsoft.com

No one was home at this time, and no computer running windows was active, so I'm pretty sure this was not legit traffic (unless it was a *very* delayed ack from a microsoft server, like > 6 hours. I guess this is conceivable, given their current, er, issues :).

Is this some sort of known "attack"? Or just random weiredness?

Cheers,

-- 
Michael Rowe 

IM  - mrowe@jabber.org                Prof - ACM, IEEE, Computer Soc.
Web - 
http://www.mojain.com/          Vice - Barley malt, brewed or
Key - 
http://mojain.com/keys/mrowe.asc       distilled (hold the ice)


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