[WorldMaker]

To my understanding, letter transpositions are common even for great touch typists. Especially letters in the same "category" (such as shifting vowels around in this instance). Sure, it's a different "feel" when typing it wrong and if you are paying attention you might catch it, but you generally when touch typing don't think about the specific feel of individual letters, but the pattern or "shape" of the overall word. "gut" is a common enough word pattern (and an English word in its own right). "hib" is not, but if your brain/muscle memory is expecting the full "word" "github" and knows it uses both fingers "in the middle of the shapes" and it already used "u" it can be a likely transposition to wind up with "hib".