Knee weakness

Okay, so this was the situation...My husband and I were talking in the kitchen (not really fighting, just expressing irritation) And I turned to walk out of the kitchen, down the hall and fired back some "scathing remark" and I got the usual facial cataplexy/head rush and also, my knees went weak. Fortunately, not so weak that I fell, but weak enough that I was acutely aware that I dodged another bullet. My husband of course being completely unaware of anything odd.