I have not seen a TiVo cancel a recording on it's own and use the "someone in your household..." reason.

At this stage if you are definite that someone in your household did not do anything that would have stopped the recording, then I don't know why it happened.

Keep an eye on the Season Pass and make sure new episodes are recorded correctly.

If it continues to occur you may need to contact TiVo support as it is a new issue I have not seen.

Peter.