A small little update to the head-clicking problem I described.
Since I reverted back to 1.1.1, I decided to "neglect" my Pleo for a few hours to see if it would encourage it to get sick.
I'm not sure if that neglect has anything to do with the randomness of the event, but either way, Elliott became sick. This time when he became sick he did not lower his head so far that it conflicted with the foot (i.e. no clicking/head-blocking-foot problem). Obviously he still lowered it, just literally a few centimeters less than when he was on OS2. Maybe it has to do with OS2's being sick? Has anyone had their OS2 Pleo become sick? (I'm starting to feel like a bad parent) And if so, did you experience a similar problem?
Luckily, it didn't take me long at all to get him back to regular health this time around (only about 10 minutes of lots of attention and feeding [he seemed to recognize his leaf better - my apartment is normally quite dim and with OS2 it seemed hit-or-miss but this time I put it in front of him like normal and he immediately put his head up and opened his mouth - three times in a row]). When I was on OS2, I spent a good 30-40 minutes trying to nurse him back to health and he still remained sick (this was around the time I gave up and reverted because I didn't want anything to break from the problem I was experiencing so I'm not sure if it's just supposed to be more difficult to nurse him back or what).
Either way, he's back to health and there was no clicking incident!