Well cool! Anything that has become that embedded in the culture, sung a million times a day by the common people, has made that transition into public domain, where the courts should recognize it as such. And did! Thank you John.
The lesson here is that what you read about how things work quickly becomes outdated and, if it is a matter of concern to your commercial endeavors, do a little up-to-date research so you don't stymie your own pursuits unnecessarily.

There will always be another song to be written. Someone will write it. Why not you? www.garyeandrews.com