Ok, I am a freak for jumping to the ED nurse conclusion (med student-itis maybe?)
But that was some CRAZY muscle cramp.
Leg is 100x better today, almost completely symptom free. I was told to "walk it off" by one of my classmates.
*And yes, I think Cartoon Characters was right--dehydration makes the most sense. I was really good about hydrating on the plane, it was the 12h after that with moving and unpacking that I dropped the ball. And yes, it was actually the *worst* pain I have ever felt in my life (not that I have undergone serious trauma but have had my share of sports related injuries to compare it to).