Retin-a for 29 y/o Female with Brown Skin?

I am 29-year old female brown skin. I have been using retin-a 0.05% twice a day (as prescribed) for the past 4 weeks. My skin has definitely improved. texture is more smooth and only have 2 pimples left. Scars slowly fading. I dont understand why my face doesnt feel dry or tight when I apply the cream, it is actually after I shower. My skin peels but disappeaes after about 3 mins. My face looks normalBut feels tight. And when I apply yhe cream again tightness goes away. Why is this happening?