Whatever is a gray whale doing here?

The North Atlantic gray whale population was wiped out centuries ago. The animals survive only in the Pacific. So what is one doing in the Mediterranean?
Cetologists are as flustered by that question as everyone else. Is it from some overlooked remnant of the Atlantic population? Did it come through the Northwest Passage and then swim south (as is considered most likely)? Did it head southwest and come up unnoticed through the Suez Canal? If it swam for thousands of miles to get to a place its species has never lived, why?
It's tempting to shriug and say Mother Nature likes to stump us once in a while. Scientists, of course, cannot stop there. This whale will have a lot of human company for a while.

THANKS to Drs. Charles Paxton and Darren Naish for passing on items about this sighting.