Hi djepson,I think this is part of the sky anytime service,When there is a few days left on certain programmes.sky will let you know when it will be taken off the reserved hard drive space that sky use for the anytime service.hope this helps.
Some movies also get you an extra message saying that it will expire in a few months time, when you transfer it from the Anytime to the Planner. It's started recently for me too but not with any consistency.
7th Feb is a Sunday. 7th Jan was, however, a Thursday - maybe this was the original day it was due to be deleted off the Anytime roster, unless people viewed/recorded it?