This has happened too many times to me, so I must speak out. My old PM's that I erased months ago keep re-appearing in my PM list.
I thought that when I erase my PM's, they are permanently destroyed, but for some reason they pop up again and again. This makes me suspicious that PM's have no security guarantees. Their storage must be haphazard if they re-appear. This lack of security increases the likelihood that they can become available to other people.
I have no big secrets on my PM's, but maybe other MN users do have (other than those secrets from Stradivari .)