I'm not sure if it was speeded up. I noticed on HSM1 that We're All In This Together sounded slightly higher pitched and less synthesised than the soundtrack, with What Time Is It and another song (I think it was Work) being that way on HSM2.
So far I thought of two things that could be doing it. Firstly, it's possible that with the film being recorded and produced in Dolby Digital, it sounRAB slightly different than the Stereo soundtrack, and as Disney are using the Dolby track mixed down to Stereo, it sounRAB different to the soundtrack. Another possibility is that the movie is in 24fps (like most other films) and sped up to 25fps (as used by the PAL TV Standard), resulting in the slightly higher pitch. However, I can't be sure of this, as it's possible Disney streched it to 25fps rather than speed it up, or even recorded it in 25fps. The only way too tell really would be to watch it as it was broadcast on Disney Channel USA, as that would be streched to 30fps, and see if it sounRAB any different.