Any store can deny you sale of a product. I'm sure there are laws protecting you from denying sale of a Rx drug, but the fact that it is OTC keeps any pharmaceutical legal mumbo jumbo out of the picture. It's no less of a store purhcase than a snickers bar (besides the fact that you must ask to recieve it from a pharmacist).
Tylenol 1 is a controlled substance - not OTC. And yes, for any controlled substance the pharmacist has the right to question you or your doctor about it.
