Do you mean the "this thread is moved here"? Not sure but I'll look into it.
If there is no function to expire it, then maybe the mods can earn their keep by spending a few minutes deleting the "Moved" notices after a few days.
See, my problem there is this...
It seems to me that if you leave the "Moved" notice up for a few days, anybody that really cares about it should have noted it along the way. In some cases, a few hours would be sufficient, and meaning no disrespect, all that is required of some posts given the content.