One aspect of absolute pitch that I didn't know until recently is that it almost always drifts when you get past a certain age. An acquiantance described how in middle age his perception of pitches had shifted by a semitone so the sensation he got for say an A5 was the sensation he used to get for an Aflat5. It got progressively worse from there.

The thing is this doesn't mean you no longer have absolute pitch. You can still identify the pitches but they feel different, which can affect the enjoyment of music. All the sensations you get from familiar music are now permanently altered, which can take a lot of getting used to.

I added this to a short list of reasons I tend to be rather glad I don't have absolute pitch.