In general, like in a lab setting, we would regard CH4 as a non-polar molecule overall. However, what has been agreed upon by the powers that be is that technically each individual C-H bond is in fact polar because of the difference in electronegativity of carbon and hydrogen. And technically this is a correct statement, no matter how small of a difference it might be.

It must also be recognized that there is a sliding scale of polarity that ranges from slightly polar like the example given, to very polar such as in water. To be fair this is getting very technical and for all intents and purposes, no one really talks about pure hydrocarbons as being polar molecules.