It's not weird, it is very common for people to spot incorrect spelling from other people's writing, ie. 'notis' (sorry!) whilst failing to see incorrect spelling from their own writing. I did some work into it at university last year.
getting other people to "proof read" essays is a good way of getting spelling better. Or you could read a dictionary or use spelling and grammar on the computer
well.; zebra is a word a the end of the dictionary, so if i was reading the dictonary as if it were a story, at the end the zebra would of caused the envents in the story to happen....