Urban legend has it that changes in pitch in commercial recordings are most often made after the fact by the recording expert, who may speed up or slow down the tape to make the tracks take up the right amount of total time on the record - or for other more esoteric reasons. Addition of "effects," and even instruments, that weren't there at the recording session is so common that one should not be surprised if the recording sounds somewhat different than what was played.

About the only way to know for sure would be to find someone who's willing to admit having done it (on purpose).

John