that in fact is possible. and the other way, too.
if the apple lossless file would have been made out of original master files, then apple lossless would be a perfect copy. if the apple lossless file would have been made out of a cd (which is only a near-perfect copy due to possible errors during burning the production master cd) then the possible read errors of a near-perfect cd track would be transferred permanently into the apple lossless version.
now if we compare a cd track to the lossless file generated from master file, in theory, the lossless file would sound better, though it's debatable if the difference can be proved with a human hear. on the other hand, if we compare a cd track to the lossless file generated from the same cd, in theory, the lossless file would sound worse, though the same applies here as in previous case.
it's all about how the lossless file is made, in other words, closer to the source always sounds better.
BUT...
a lossless is a lossless is a lossless. is there a professional designer who says that TIFF image changes between multiple saves? take a JPEG (lossy) image and save it a thousand times, and you will see a difference. take a TIFF (lossless) image and do the same, and compare it to the original - bit by bit - and it has remained the same.
and the same goes to lossless audio. a lossless coding means lossless audio, in other words, even though the audio FILE becomes smaller, the audio WAVEFORM can be re-constructed 100% matching the original.
difference can be made happening, but it will not become from lossless coding, if the "apple lossless" is truly a lossless method. i have myself not yet proven this, so i have to trust that apple knows what it says.