I make mistakes like this all the time. Septmeber is a word I frequently mistype, hte comes out pretty frequently, adn so do quite a lot of other words.
Software designers know very well that our brains sometimes screw up what we want our fingers to put through the keyboard. You only have to look at the autocorrect list in a word processor to see the common ones. They aren't all mis-spellings: what;s, virtualyl, understnad, wnat... I don't think anyone need be paranoid about it.
A research team I knew fairly well were testing how observant people are of mistakes, by providing a "disobedient keyboard" which made typos even when they were typing correctly. Most people knew they had really typed a word correctly, even though it appeared wrong on the screen. You sure you haven't got a bit of their equipment there?