The X1/X2/4800 were changed to 4000 hours lamp life by firmware update - there is no such update available (yet, anyway) for the 4805.
AFAIK, the 4800 is really an X1 in disguise - however the 4805 is not an X2 in disguise.
Apparently there is a risk that that the bulb will burst and damage the projector internally - however the lamp life chosen is a little arbitrary (after all, I doubt they are suggesting that at 2990 hours there is no risk of this, but at 3010 there is - however if you bother with a limit at all, you have set that limit at some figure or other), all they are really saying is that the risk of this happening increases with lamp age, and at some point, with average use, the statistical risk becomes a bit too high.