you mean when your skin gets tight? thats a normal sign of dryness. Its usually worse when you wash your face and as your skin starts to dry it tightens until you apply moisturizer - which is what you need to do to stop the dryness.

It cant cause the skin to sag but when your skin is that dry it can temporarily wrinkle. emphasis on temporarily because it will go back to normal once your skin is back to normal. People tend to freak out when that happens and think whatever acne medication theyre using is 'prematurely aging' them - not the case.