Good to hear the reason for your hospital visit turned out to be something harmless.
There wouldn't be much use of an encrypted LVM if the password could be stolen by hackers. I would ask questions on any GNU/Linux forum as I'm not a security expert, but how would someone steal your password using the Internet before any of the Operating System components have loaded? That's very different from e.g. using encrypted volumes on an internet-connected computer that could be compromised.