I have an Infocus SP-5000, about two years old, with ~700 hours use. It is working well, but now is showing two lighted areas in the upper right quadrant of the screen when the picture is black. They are elliptically shaped, and dim and diffuse, so even minor light on the screen washes them out. I mostly notice them during closing credits against a black screen. They look like some kind of reflection from stray light. The color is pure white.

Has anybody seen anything like this before?

Dust on LCD or lens?