[dfan]

I agree with all of the above, including the hypothesis that the OP likely had absolute pitch to some degree as a child and not thought about it. Everyone I personally know with perfect pitch (including myself) started engaging with music seriously very early on in life. (I don't know quickly I acquired it because it's always been as easy as identifying colors and I didn't know it was unusual until my piano teacher noticed.)

For me piano is definitely the easiest instrument to identify, I'm sure largely because it's what I've played all my life. Pipe organs are the worst. I assume that in general the purity of the tone correlates negatively with ease of identification.