And my messiness bites me you-know-where

Today’s practice was rather weird, at least at first.
As opposed to a upright or some size of grand, we have in our house an electric keyboard. It’s unweighted – meaning I’m absolute rubbish when I’m at a real piano – but I love it anyway. I usually leave it in the piano setting, though occasionally screwing around with the sounds (most often pointedly avoiding the synthesized oboe and English horn). When I practice, I play in front of it, to play parts on it for rhythm or, more often, intonation. It’s at 440 Hz rather than 441, something that annoys me, but I live with it.
I tend to leave music scattered all over it as well as all over the rest of the room. It’s a problem.
Today when I sat down to practice, I fiddled around on the piano while my reed was soaking. I thought some things sounded funny, but I couldn’t quite figure out why; I moved music off the speakers, restarted the keyboard, but nothing changed. I eventually decided it must be something I’d never noticed before and forgot about it.
I warmed up on oboe and started doing scales. After a few runs I checked my intonation on the keyboard and realized I was a half-step flat.
Odd, but I wasn’t bothered. I changed reeds, making a mental note to bring the pitch up on it later.
The next reed was – exactly the same. A half-step flat. I crowed it (or, played just on the reed) and it was well in tune. No cracks that would explain the drop in pitch. Nor, frankly, cracks in the oboe.
By this point I was at a loss.
Until – I noticed a large etude book on the left speaker. On the left end of the keyboard, there’s a wheel that, when holding a pitch on the keyboard, warps it sharp or flat (up to a whole step either way). It looked as though the book might have been resting on it and – maybe, just maybe – moving it up in pitch.
Sure enough, that was it.
After moving the book, everything went back to normal – or at least to how it was yesterday.
I wish I could say I’d learned from this and no longer keep books lying on the keyboard, but that’s most certainly not the case. I just keep them all stacked slightly more carefully so they don’t touch any buttons.
So far, so good.