LCD color fades after a few seconds, horizontal lines appear

I just finished replacing the front panel on my wife's iPhone 3GS. The touch digitizer works flawlessly, but the LCD is not performing as it did prior to replacing the front panel. This is the same LCD that was in the phone prior to replacing the front panel.

When the LCD starts to display, the picture looks fine, but gradually, the color fades and the image looks "shaky." Faint horizontal lines appear in the image. The image seems to stop deteriorating after a few seconds and remains faded, "shaky," and with faint horizontal lines across it. Pressing the lock button to shut off the display and pressing it again to turn it back on returns the LCD to its normal state, followed shortly by the same deterioration described above.

What could be wrong?

Update: I reconnected the LCD connector several times and even tried it without the digitizer connected, and the problem persists.

Update: I took the front panel and LCD assembly out of my phone and connected the LCD to my wife's phone and it displayed fine. I then took the front panel and LCD assembly from her phone and connected it to mine, and it showed the symptoms on my phone as well, so it has to be her LCD. I don't know what could have happened to it while replacing the front panel, though. It was safely stored a few feet away from where I was working, and it wasn't disturbed until I put it back into the phone.