I was thinking this coin might have some friction on Liberty's breast and thigh, plus some loss of luster in the right obverse field. In that case MS-61 might be a net-grade with the grader feeling an AU-58 would have been too harsh.
If the fields in-hand have full luster then the assigned grade does seem low. The price goes up fast for higher MS grades; this coin might be worth cracking out and submitting to PCGS. Even an MS-62 would repay the submission cost.