In case you were wondering, yes, these things do happen, which is why one should usually take a quick look, or a longer one as the case may be, at the session law, at least in those instances where something doesn’t seem quite right about the code.
A code is not usually official (though sometimes it is, e.g. some USC titles – and some jurisdictions don’t codify, at least not officially), but codes are generally deemed prima facie evidence of the law (e.g. USC). See here for more on this and here if you want to learn lots more about legal research terminology. And don’t forget this terrific guide to “How to Research a Legal Problem: A Guide for Non-Lawyers.”