I read it. It still doesn't compute. There's really no reason for increasing IQ after a simple (un)screw! And even less reason for said IQ to remain higher for hours afterwards.
Well, it's like I said...when trying to get a better contact on a car battery, there is a little tool us mechanics use, to rough up the surface of the battery post, so that cleaner metal is exposed to make that better connection...

The inside is lined with little wires (like a wire brush).

You put it down over the battery post and spin it.
Once you've done this, there is "raw" metal exposed...which makes a better electrical connection.
SO...*takes deep breath* this is what I was referencing when I said turning the cap on your P3 can POSSIBLY make a better connection, providing a better IQ reading.
In an electrical circuit, like the one created between your battery, the chip's contact, and the spring...let's just say that carbon builds up on a very small level, at all those points...as evidenced by the little black marks you can sometimes find on the ends of your battery. When you clean those off, you create a better contact surface...
What I'm proposing, is that the IQ feature is sensitive enough to notice the microscopic build up of carbon, during the single use of a battery...and if you turn the cap, you're turning the spring against the battery, and the battery against the contact on the chip, "scratching away" that carbon build up.
My thoughts only. Not fact.
PURELY SPECULATION.
But speculation based on a series of factual experience(s)...