Have you ever seen a grammatical error in a book?

I have - and I've seen errors in sayings as well. You know the one that says someone is 'to the manor born' - meaning that they behave as though they were nobility etc.etc. TWICE in one week I read books that used the phrase 'to the manner born' - which tells me that the proof readers were asleep at the switch, or there was no live proof reader used, just a spell checker.