First I hear of red blotches in your face as a hypo symptom (but then, who checks a mirror when having a hypo, I might have green hearts on my forehead for all I know!), but if they disappeared after you got your blood glucose up a bit, I'd just assume it's an odd hypo symptom.
While you weren't hypo technically, at 4.1, your body might still experience this as a low because you're used to higher numbers.
In fairness, it's a rather practical hypo symptom, if that's what it was, easy for others to spot and nudge you to check your BG!