Apology accepted.

Now...The Hard part...... Do you understand what was fixed on your car and WHY???

Somewhere along the line, your car decided that the engine was turning too fast, and the wheels werent going fast enough. This may have been subtle, or extreme, but it did happen. Your computer noted this condition on two consecutive trips.

Now....In his mind, the Gear ratio is incorrect, based on what he sees. The speed sensors and "Shift solenoids that control the shifting of the trans, are all built INSIDE your trans, and linked to the computer thru that little round " ADAPTER PLUG".
When it leaks, fluid gets into the electrical terminals, and changes the resistance, or Corrupts a sensor signal, and the computer sees a situation that he is not capable of handling.

It boils down to this.....A slipping trans, or electrical failure, or fluid leak inside the plug, will ALL cause the same Information to be recieved at the computer, and will ALL cause the 730 code, and will ALL turn on the check engine lamp.

Codes ONLY point you in a DIRECTION...they arent the FINAL WORD, OR ULTIMATE LAW.
I also Apologize for my Comments, ( Although I really Despise The AVALANCHE:)) But understand something......Due to the complexity of todays vehicles, The general public Doesnt have the understanding of their cars , such as they did 30 or 40 years ago. I do realize that there are mechanics out there without a conscience. Working at a dealership doesnt instantly mean I'm a thief. Just think for a moment...Your Identical situation, and a customer who comes in and ASKS "How much will you charge me to replace My "GEAR RATIO"....because . Thats what the scan Tool says is broken. It happens ALL THE TIME.....

so in a nutshell should i take it to the dealership and have them check it out again. just to make sure everything is ok with the transmission?

No....

If the C/E light didnt come back on, there is no need to do anything more with it.

However, I would leave a piece of cardboard under the car for another few days, just to monitor for any leakage.. In case you havent noticed, You CANT check your trans fluid, so any drop in level will usually go un noticed until its too late.

you are absolutely right. and no the check engine light didnt come back on and i did not put cardboard down to check for leaking but i will. P.S. knowledge is so freaking hot and thank you you are the best. :-)

My 2005 300C transmission slipping
 

When transmission warms up it slips the code says 1st and 2 nd gear ratio is off what do I need to do to fix the problem .