Could be
I remember hearing about that last year. Here's an article on the story. It's entirely possible.
And let's not forget the Vikings. There's a lot of evidence they got to the centuries before Columbus
Then again, there's a claim that an Irish monk who supposedly crossed the Atlantic long before Columbus and the Vikings.
Funny thing about claims of "discovering" America is that millions of people were already here and had been for thousands of years. You and I might as well go claim to discover Japan.