Hi, David.

At times I've noticed similar come about via other users, I believe always outside of the US. I don't know what the reason for the issue is.

A year or so ago a moderator in Brazil tried multiple times (while we were both actively communicating back and forth on a particular Content Issues thread) to reset a particular date, though each time he tried anew it kept showing as being one day off. I'm in the US and reset it, and immediately the correct date saved.