The Roomisode X and Playable Rig Rug updates introduced a few new tunes to the game; it's only reasonable that they'd make it into the downloadable soundtrack.

I'm surprised it hasn't happened already. Maybe the soundtrack-makers got raided by the Feds in the middle of rigging rugs and dodging paint-spewing robots. Or maybe they got their documents, secrets, and notions stolen by a clown-faced assailant wearing a flower hat and barf-stained bib.