How? That's pretty serious effort to bend a skewer in situ. Someone I know once slightly bent a rear QR on a single speed, but in fairness, it should have had a more solid axle.
I'm just pleased you've found out without hurting yourself Jim.
My own experience is that all the skewers with the Hope type cam on the end of the lever design (I've also used Kore and the ones with "pat 71510") tend to work loose when used with a suspension fork. Shimano ones open from the fully closed position a few degrees but then stop. After a friend's front wheell came out and he broke his collar bone I've relegated all the non-Shimano skewers to road bikes with lawyer tabs.
Never had an issue with Hope steel skewers, yes I do them up pretty tight, and sometimes it can be a bit of a hassle getting them open again at the end of the day, but never had any issues once they are done up!!!
I should make clear that 'work loose' doesn't necessarily mean the lever has visibly moved (but on occasions has). It means that the wheel has moved in the dropouts leading to disc brake rub and/or the QR was significantly easier to undo than it should have been given the brute force needed to close it.