I’ve occasionally noticed that my /uː/ in English is not [uː] but something further forward, perhaps [ʉː].
Recently, I’ve noticed that Amy’s realisation of that phoneme seems to be even further forward. At first, I thought she had merged it into [yː] from German /y/, but I think it’s not quite that far forward.
Still, hearing her pronounce, say, spoon as [sʉ̟ːn] sounds odd to me. Perhaps it's just that she's get a “real” [ʉː] while I’ve merely got a [u̟ː] or whatever. At any rate, it reinforces the fact that my /u/ is not an [u].