The list of name servers given to us from the root does not match the list published by your name servers.
The DNS check requests the NS records for the requested domain starting from the Root servers and continues following referrals as long as the Answer returned is not marked as Authoritative. Once we have gotten an Authoritative response, we compare the list of NS records in that answer which we are calling Local to the list of referrals given to us by the immediately previous response, which we are calling the Parent.
A discrepancy between these lists signifies that either the NS records on your authoritative name servers are incorrect or that your have failed to update your parent records. Parent records for second-level domains are usually controlled at the domain's registrar.
Missing NS records can cause delays for clients when resolving your records, as they attempt to contact a name server that is either non-existant or non-authoritative. Extraneous NS records can cause havoc if they point to name servers that are not being kept current, or worse, if they are no longer under your control.