My personal theory is that it is very, very easy to get to America - it's difficult to leave! (using pre-modern technology).
Concerning reporting the existence of the New World to the Europeans, I wouldn't have considered it myself until the mid-1400s when Europe was less barbaric. The Chinese knew about it, visited it, and turned their backs on the opportunities. The Byzantines may well have made a few voyages of discovery. Third century Romans from Mauritania probably made it to near Cahokia, and so on.
I believe that Peru will eventually be proven to be the location of King Solomons mines. (Accessed up the Amazon River)