Toyota Yaris 1.0 VVTI with the MMT gearbox warning goes neutral

Hi guys I have been reading some of the posts already about this problem but basically I have a 2003 Yaris with the MMT gearbox. It has 108.000km and last week, the gearbox start behaving weirdly.

While I was driving, I went from 4th gear to 5th and the car went neutral with the red warning in a gear with a ! in the middle of the icon. I pulled over the car and turned it off for a minute and when I turn the car back on, it started working correctly.

For what I know I'm the second owner and I'm sure the gearbox oiled was never change but I don't think it can be the actuator problem everybody is talking about since the car has only 108.000km.

Any suggestions? Thank you.