Wicked Yankee Girl
Since she's disclosed that not telling the whole truth about her health is a strategy, it's hard to quote what she said in an interview as a final source, until after she retires and writes a second book.
However, the fact that she was able to recover rapidly and skate the second half of the program, and skated the gala (magnificiently, I might add) the next day does argue that it was a cramp and not a severe recurrence of exertional compartment syndrome.
Perhaps her efforts to reduce strain on her lower legs is what is causing the cramping in her upper leg. I recall that Plushenko's efforts to reduce impact on his knees several years ago resulted in two hernias because he was stressing his abdominal muscles.