Installing the siding "too tight" by driving the nails too deep or by not leaving enough of a gap at the J-channel can certainly make the problem worse. But I've seen this happen to high quality vinyl siding that was properly installed, even in the center of long walls where room for expansion is no issue. The reflected sunlight can get the siding so hot that it just melts it in place. This happened in upstate NY which is not known for its intense sunshine.

There's a thread on this problem at The Inspector's Journal forum that has been kicking around for a while. In that one, the siding on the house is being damaged from a reflection off the window of a neighbor's house. Now there's a tough solution....