Let's see if you can figure it out in 1.1.0, I made few changes that should better guide players to getting it. :^)
Just found it on the second play through! It wasn't another pinup sadly, but well worth the search nonetheless. ;D
I also had an issue during the first boss battle, where the music track played once and didn't loop again. Might have been a symptom of my quickloading, though.
Damn it, you're not the only one who had the music loop problem, and I have no idea what may cause it or how to fix it. Trust me, I racked my brain along with some of the testers and nothing seemed to work. :s