You guys were all absolutely right. I ran a few re-creations of the traumatic event and I'm 100% certain that either:
- I didn't TOTALLY get the door shut when I closed it, or
- I used the keycard and the phone key wasn't properly connected (my phone bluetooth is finicky). This is something I would forget about and not register in my tiny brain.
Thank you all for chiming in about this, and I hope that my idiocy might serve as a reminder to everyone to be careful. It gives a lot of credence to the old quip, "it may be that the purpose of your life is to serve as a warning to others."