I must admit I've never come across SD cards bending, however after inspecting my SD Card adapter that too appears to be suffering from the bends and cracked corner (after 2 years solid use).
From a personal point of view I can see the Pi SD Card holder having a serious design flaw.
The SD Card is only held by the edges but there's no support for the top lip or face so when fully inserted the contact pins are effectively pushing from underneath out without equal pressure from the top.
Due to pressure imbalances I suspect micro fractures over time are created in the plastic structure and this eventually lead to warping or cracks.
Incidentally there has been reports of SD Card holders cracking at the sides which frankly doesn't surprise me given the pressures involved.
If you're Pi user who values your data I would strongly suggest inspecting all SD Cards for physical damage as well as corrupt file systems.
Fortunately I have another spare micro SD adapter at hand but if this was a real SD Card I dread to think how it would affect the memory chip inside and gold bonds for that matter.
I might actually remove the SD Card holder altogether and replace it with a Micro SD version but I haven't found a spring loaded one that's PCB pin to pin compatible yet.
Alternative if anyone knows of a better SD Card holder that supports the card on the face and lip then please let me know.