This happened several times yesterday; once I composed the reply and hit the trackball I did not get the send option.
I tried pressing the nav button and there as well there was not an option to send. So after being on the phone with tech support and doing a system wipe I went into the store today to get a new handset.

One other issue I was experiencing was with the inability of the bluetooth to sync with with my headset - fixed with the new phone. Other issue was also that the trackball does not click all the time when scrolling down through the emails ... just strange!

That's for this evening! Happy New Year!