[Gaffer]

I’ve got a 1911 that’ll do that. Never keep one in the chamber.

[Spktyr]

Your 1911 is broken. If it drops the hammer when its dropped (and not onto the hammer) then you need to have it fixed.

[andy58-in-nh]

With a 1911, you ought to have not only a thumb safety but a grip safety as well. That's why the standard carry condition is cocked and locked ("Condition 1"). If I had a .45 that did that, I'd take it to a gunsmith, pronto. In this poor guy's case, I'd still bet he caught the trigger somehow. Regardless, I learned a long time ago that cheap holsters are not worth the risk. Get yourself some good leather, work it in properly, and if you have to go to the mens' room while carrying, make sure you know where all your weapons are at all times. ;-)