Mine's been doing that for the past couple of months. I'd say the flyback's on its way out.
It won't blow up and kill you, but when it goes out, it won't smell all that nice either.
Well, strictly speaking, there's no flyback in an LCD-based display, but there is a high-ish voltage transformer that can go south. It generally doesn't emit (many) malodorous fumes, though -- the transistors driving it typically fail first, preventing the transformer from cooking too long.
Flickering of the backlight is generally the result of a crimped cable, a bad inverter, or a bad CCFL tube. It's not easy to determine which of these is the problem without some instrumentation, but here are some general guidelines:
1) A crimped cable will usually be sensitive to flexing of the display lid. So, if moving it around affects the flickering, then a crimped cable or other loose-connection type of problem is the cause.
2) If the backlight is somewhat dim when it's working (particularly if the light seems more yellow than white), then the CCFL tube itself has reached its end of life.
3) If neither 1) nor 2), then suspicion falls on the inverter. The intermittency may be due to something as simple as the fact that it got wet, and some conductive residue remains. Or, it could be more serious, such as failing insulation in the CCFL wiring, or in the inverter's transformer. If you hear gentle (or loud) sizzling sounds, then a failure in this neck of the woods is likely.
