Anyone know why this wouldn't be valid mbox format?

[me at prestoncrawford.com (Preston Crawford)]

Trying to get my wife's emails out of a proprietary format and into mbox
for use on our local box. Doing some major file munging. In a test email
the following doesn't work. (forgetting dates, email addresses, etc.)

>From heraddress@xxxxxxxxxxxxx Wed Oct  10 11:50:44 2005 -0700
Date: Wed, 10 Oct 2005 11:50:42 -0700 (PDT)

This does work

>From heraddress@xxxxxxxxxxxxx Wed Oct  9 11:50:44 2005 -0700
Date: Wed, 9 Oct 2005 11:50:42 -0700 (PDT)

This is just me munging files and trying them in Pine.

Any idea why the first doesn't work and the second does?

Preston