Yes, I have the same issue. I get spurious 'light ups' fairly frequently. Most of the time it happens it displays 'line error - please correct', sometimes no message - I suspect that when there is no message, it is because the 'error' has cleared very quickly.
When it happens with me, if there is a 'line cord error' message displayed, then for whatever reason, the error clears and the phone goes to the BT logo screen for the usual timeout period and the reverts to the screensaver.
If, as sometimes happens, the screen lights up and seems to go straight to the BT logo screen for the usual timeout period. In these cases, I think the 'line cord error' did likely occur but cleared immediately.
I don't know what it is, and can't find out. There are others who have the same/similar.