Doesn't sound like a torque converter issue, more like a learned response to your driving.

Are you the only driver? The main driver?

Disconnect the battery for an hour or so and see if it still does it. If it 'fixes' it, then the Transmission Control Module (TCM) has learned something that made it act that way. If it's acting the same when you reconnect the battery, then there's probably an issue and you should take it back to the dealer with your complaint.

Don't try to tell them something that you think they'll act on, tell them exactly what it's doing/not doing. The TSB's that the techs have access to nowadays are pretty specific. I don't see anything for the '09, but they can always call Tech Hotline with the complaint and get the latest and greatest.

I'm betting you're going to end up at the dealer anyway.