No, it has never occurred. I've been using it in ecomode for a few months without any problems so that the fan runs quietly. The brightness hardly differs from normal mode.

Yes, I also have this problem sometimes. Everything ran tip-top for about half a year and then it started.
I then switch the projector so that the lamp gets full power and then back again later. Then the problem is usually gone. You can also read about this on forums.