Can't say for sure but would think that in the Southwest or even here in Chicago during the middle of June or July you could have heat in your car get hot enough to do such damage if parked in the sun. I have gone out to my car on a cold January afternoon to find the dashbord quite hot after being parked in the sun for a while.

In fact, I have some faint recallection of somone mentioning some years ago about leaving a binder full of chips in a hot car on a hot day. In someplace like Las Vegas I could only imagine that it might be possible for damage like that in a hot mailbox or delivery truck or whatever.