Wouldn't such an occurrence involve an overhaul of the world on part of some Force/Entity? And why would you, and only you, be able to note that something changed, i.e. that you believed 2+2=4 and now you no longer don't? Much more importantly, since you use it as an example, Winston would not bother to write about 2+2=3, he would probably actually write about 2+2=4, or even 5, thus shaking your world even further...