Reversing phase question

Archived from groups: rec.audio.pro (More info?)

I've got this one mix that is done, finished, burned, duped, finito - yet I
keep screwng with it at the house for months. There's a stereo acoustic guitar
pass & I have those pretty wide L/R. Suddenly the guitars sounded out of phase
so I reversed phase on one side & it seems right - how did this change if it
did
- or it's just me.