Will check again today. I see in my manual that there is a menu to turn on/off text message notification through SYNC, and I have made a habit of putting my phone in the cubby underneath the centerstack as soon as I get in so I don't usually look at my phone until I get out of the car.
Just thought that if the SMS didn't work the screen wouldn't have shown "Message Sent" or let me type the message at all. Would have expected a "Feature not available" or similar message.