My 1999 2299L Classic has no evidence of any buckles. It spent most of it's life in Southern California and I live in Eastern Idaho, also a very dry area. No evidence of any leaks.
I would suspect water damage too, but I don't know if there was a difference in the way the panels were constructed in more recent years. If so, that may be a consideration. It seems to me that in some other ways, some of the newer Hi-Lo's were not built quite as well. Just speculation here, though.
1999 22L Classic
2008 Toyota 4Runner V6