I don't know, but I suspect that everybody experiences this thing I'm about to describe.
When I started learning flute, just 3½ years ago, I worked on a very few tunes – things like The Galway Rambler and The London Lasses – some nice flute fundamentals. I worked them up until I thought I was pretty good at them. But, being a beginner, they were probably pretty rubbish.
I’ve moved on to all sorts of other tunes since, but I do get the ‘old’ tunes out and dust them off every now and then. What I find is that I’m making mistakes that I recognise as the sort of thing I did when I was first learning those tunes, but don't otherwise do now in other tunes (there are other horrors which I perpetrate now

). I find it really hard to get over those mistakes – but only for tunes learned when I was more generally prone to such mistakes – things like errors in timing, flubbed fingers, poor rolls, you name it.
I find it strange that I seem to have retained a sort of memory of these errors attached just to particular tunes.
The good news is that, although it takes some effort, I can eradicate those errors even from these ‘beginner’ tunes.
What
is this about? I find it puzzling. I suppose somebody is going to tell me it’s ‘muscle memory’, but I’m not sure I believe in that*. If you think it is, could you convince me of its existence? If it’s something else, what is it?
*One of the reasons I would discount ‘muscle memory’ in this particular case is that I can play tunes on flute that I haven’t played on flute before, just because I know them on fiddle. So I
think I play from knowing where the notes are rather than by rote discipline of my fingers. But I could be wrong …