I think there's enough evidence to support it, personally. And given the ice caps at the time, not even all that hard to believe IMO.
The more time that goes on the more conventional wisdom is tossed out the window. Columbus the first "modern" European to discover America has pretty soundly been debunked, for instance. Evidence has been found the Chinese made trips to the west coast. Heck, I seem to even recall the Egyptians and Greeks may have had some trade routes to the Americas. All of this would have been limited, but evidence has suggested the possibility/likelihood.
Who got here first is really a moot point, but is interesting all the same.