IAWKelly
IME, some aliases are absolute, while others seem to be relative.
That is, certain aliases continue to 'point' to their originals, even after you rename the HD they reside on, while others become 'hoplessly lost' if you rename the HD, or even the folder, inside which the original lives.
I do not know why some behave one way and others act differently.
But I concur with Der Searchmeister that this is the likely cause of your Mac's periodic requests for its 'old disk'.
IMO, once you delete, replace, and / or 'fix' the errant aliases, your 'old disk' yearnings will cease.
- kbeartx