Is there a recall on the transmission in a 2004 Buick Rainer

You aren't the only one to encounter this problem. But I haven't detected a recall for this.

Check for low transmission fluid. However, you may have a failing transmission. If the fluid is dark or smells burnt, you may have such. Some suggest possible savings from installation of a used transmission or a Japanese one, if that is the case. But before such considerations, examination of diagnostic codes is the route to go. .https://honda-tech.com/how-tos/a/honda-civic-why-does-my-automatic-transmission-slip-into-false-neutral-when-warm-376007

No there is not, sorry.

Take it to your GM dealer to see if there is an outstanding recall on this issue. I could be something as simple as a vacuum leak or a bad cruise module. I wouldn't wait on that problem.

Possible, but make sure you have correct fluid level. Start car and let idle for 15 minutes, fluid level is checked with engine running.

check fluid level, if good it maybe electrical problem..
check with dealer for recalls

On this website you find fuse box diagram and description for Buick Rainer (2004)

http://www.carknowledge.info/buick-rainer-2003-2006-fuse-box-diagram

Pretty common problem with these. Here's a guide to learn how to fix GM instrument clusters yourself, I used it to fix mine and it worked great.How to guide for Rainier instrument cluster repair

Have you checked the transmission fluid level?

There is a recall for the transmission that involves your exact problem. Call a dealer and see if your VIN is eligible for the recall. Check the NHTSA website for the exact details.

Down the dipstick tube.