LCD = Liquid crystal Display. http://en.wikipedia.org/wiki/LCD
Some issues with LCD display can be the Liquid itself. The sun beating down on it, pressure differences, just things that would effect the liquid in them.
If you have ever heard of the "Rubbing" a bad pixel out, it was all about moving the liquid around to try and get it working again. It does not work for pixels that are "dead" electronically but it may change things for pixels that are "dry".
All the ways that liquids could have moved in your travels, could be what changed the . . . liquid.