RJH presented the following explanation :
Yes, happening on mine too. I just press 'No' when it asks to retune.

There was a genuine need to retune several days ago, PBS (I think)
added a +1 channel to the lineup.

Bedroom TV, which I thought I had retuned not too long ago, wasn't
complaining, but was showing Yesterday on channel 19, instead of the
present 25 - so I retuned last night to bring it into line.