No. For me, this happens when I send a message through the web interface, but not when I send through mail.app. I'm surprised you're having any trouble at all with gmail. I take it you are following the instructions gmail supplies? As i remember there is a certain port you have to open...
Perhaps you need to change your settings? I'm guessing that this is the page you need to change (these are my settings):
I have the same configuration and yes, I followed every instruction they posted.
But I still have troubles with their pop server, because Mail pretty often can't connect to it.
BTW, I have opened the correct ports and use SSL.