As has been stated, a loose or damaged screen wiring harness could be the cause of the issue, provided the laptop has suffered some impact. They don't work themselves loose over time, as there isn't that kind of tension on them in the way they have been assembled. I'm not saying it is impossible, just that it has a low probability.
Replacing a screen inverter is essentially just as complex a job as replacing a wiring harness. You'd have to remove the bezel around the screen, and most likely remove the LCD panel itself to be able to get at the inverter and remove it from the bracket it is attached to at the bottom of the screen. You'd know if it was an inverter that was going, because you'd be able to still see what was being displayed if you pointed a flash light at the screen while it was dark. However, they don't tend to flicker when the screen is moved or opened/closed. Some will flicker when they are going bad if you tap the bezel at the bottom of the screen though.
It is more likely that the issue is more expensive. Most people open and close their laptop screens from one corner of the lid, rather than from the center... or evenly holding both corners. Over time, opening from one corner puts a twist on the screen and over time, the LCD panel separates from the PCB mounted to the top edge of the screen. For some people, this manifests in colored vertical lines on their screens that will either show up or even disappear when pressure is put on one corner or another.
Now... checking to see if the wiring harness is loose or damaged is most definitely part of the diagnostic process. Why? Well, it costs you nothing but time, and by doing so, you either discover or eliminate it as the cause.
There is also a VERY small possibility that the issue is the CCFL (cold Cathode Fluorescent bulb) itself as well. In one case with an HP laptop, the wire at the left side of the bulb had actually burnt off the bulb. The bulb itself would still function (when the wire was re-attached) but otherwise obviously would not light. But again, you can use a flash light when the laptop is on to see if it is the bulb or inverter.
So... time to take apart your screen, and see if it is the harness. If it is still connected soundly (at both ends), and there is no damage at any of the places where the harness bends, then you are looking at replacing your screen.