Nope, the date is when the message creator finalized the message prior to transport, not when it was received by any host in transit (which would be part of a Received: trace header). To quote the RFC (section 3.6.1, "The origination date field"),

The origination date field consists of the field name "Date" followed by a date-time specification.

orig-date       =       "Date:" date-time CRLF

The origination date specifies the date and time at which the creator of the message indicated that the message was complete and ready to enter the mail delivery system. For instance, this might be the time that a user pushes the "send" or "submit" button in an application program. In any case, it is specifically not intended to convey the time that the message is actually transported, but rather the time at which the human or other creator of the message has put the message into its final form, ready for transport. (For example, a portable computer user who is not connected to a network might queue a message for delivery. The origination date is intended to contain the date and time that the user queued the message, not the time when the user connected to the network to send the message.)

If you really want to make sure your email is correct in formatting, I would highly recommend you give the RFC a once-over.

Hope that helps.