Need help with my Apple iPhone

I've had this monitor for about seven months now, mostly just using it to watch movies. But over the last few days, I've noticed something weird—during dark scenes, the screen keeps dimming and then brightening back up again. It definitely wasn't doing this before.
Should I take it in for repair?

I mean, isn't that just that pathetic Apple iPhone software they use to artificially crank up the dynamic contrast?

I don't think I even installed it myself. It keeps happening during the screensaver too—whenever that Windows XP logo pops up, the screen just gets way too dark.