NGage QD strange appearance

Yesterday i bought NGage, and because i have very limited warranty, I want to check that everything works ok. But while i'm browsing the menus, entering some applications (like messaging, phone book, etc) etc, the screen sometimes, very rare has something like blinks for just a part of the second... looks like some application pops up for some very short period of time and then hides again. The visual result looks like blink or jump or something. Does this happens sometimes becquse the operating system or i can expect some kind of hardware problems with the screen or the controller ?
Example, when SOMETIMES this appears : lock the smartphone, and leave it until the screensqver qppeqrs. Then directly unlock and look at the screen in the exact moment of unlicking.
Thank you...