How long would Creatine Kinase (CK) levels in blood be high after exercise? Symptoms? Other ideas?

Two weeks ago I took some routine blood tests after visiting the doctor for another issue. Today I got the results of those blood tests which showed high Creatine Kinase (CK) levels. From what I remember it was about 1100 while 'normal' is about 200. (Wiki offers range of 60-400)

The doctor and I are both puzzled as to what might have caused this. Doctor actually asked if I was sure I hadn't had a heart attack. I don't have any heart issues or muscle pain. Not taking any medications beyond a multivitamin and a half serving of protein powder 4-5 times a week.

I was somewhat ill when I had the blood taken. Just a cold.

Only thing I can imagine is I did a few P90X videos the week before the blood tests were taken. From what I remember, the last one was at least 5 days before. I didn't think those workouts were that bad.

The only real symptom I've been feeling in the past few weeks has been a general light headedness. I'd assumed this was just from being tired/stressed.

Any ideas??