appraisal price comes out $6K lower thank sales price, what i sh

Recently bought a house, received appraisal price today, and it is $6K lower thank the sales price. Is this normal.  I studied the appraisal. I feel that it is not fair to the house.  The house i purchased is on the lake with backyard facing Michigan lake and view of city skyline.  The three houses compared with the house i purchased is on the other side of the street. Should I argue with the appraiser?

Thanks

Fenghua