8 days ago. I had my 4th session of microneedling with hyaluronic acid. Light redness & traces of blood still left.

At time of 3 sessions my redness & traces of blood gone into 3 to 4 days but this time at my 4th session light traces of blood & very light redness still I have. I took my 4th sessions gap of 2 weeks according to my dermatologist. At 4th session my doctor use 2 or 2.5 mm. I feel worried. After 8 days why I have still redness and traces of blood in few areas? Please answer my question. Maybe 4th session was done with aggressive. Don't know please help!