The onboard computer sometimes produces false reports. However, when even a false warning is reported, it generally indicates that the computer has detected something wrong, and that a particular aspect of the cars operation will fail eventually. For instance, my 2006 3.0i produced the yellow engine warning light, which according to the owners manual, refers to "deterioration of exhaust emission values". I got home and turned the car off, had dinner, then returned to start the car an hour later. There was no warning light, and the car was fine for several days good driving, then low and behold, the engine warning light reappeared and remained emitted permanently. The dealer found the fault - a leaking air pipe that required replacing for $136AU. On two occasions recently, I have seen the red tyre pressure warning appear, which goes away after I press the tyre pressure calibration button located under the air conditioner system, but I am suspicious that the computer has detected a fault and that the warning will appear permanently emitted after the tyre pressure has failed completely.
These two examples highlight the general behaviour of the onboard computer, and in your case, the car may be absolutely fine, but if the light reappears intermittently or permanently, I would get your cars transmission checked out.