yes that IS odd. But I definitely changed the font size one step down, went out, ( I even turned it off and back on and went back in just now) went back into the same book and the problem is completely gone... weird.. Oh well.
Will be nice to get the firmware update tho as I prefer a slightly larger font, but I can't be bothered messing with it to get the magic combination of formatting settings where it doesn't happen with a larger font..