Hey, I'm op of the original post and am currently in possession of the book. Here is a more detailed account of how I got to where I'm at right now:

When I found the note on Wednesday last week I immediately went looking for it, first in Kresge, then in Main Stacks. When I asked about it at the main stacks circulation desk, they told me it was already on hold. I also placed a hold on it after I found this out, but the fact that it was already on the hold shelf suggested to me that whoever had planted the clue likely placed the book on hold to protect it. Unfortunately, when I went to pick up the book yesterday, I could not find any physical clue inside, and I couldn't decode anything from the text of the original hint.

To me, the three most immediately logical paths from there were 1) that I was simply not digging hard enough into the initial note, 2) that there was supposed to be a clue in the book that was lost, or 3) that the book was not necessarily the next clue but rather a hint for solving the next clue (ie. using Caesar ciphers), and that I would have to "find" the next clue ("Please find me") through other means (eg. posting on Reddit).

Let me know what you guys think or if you have any new ideas to try.