Unexplainable difference report figures

Content

Hi there,

To see answers that were visited I have two reports that show different figures for the same month (May 2017): 

The 'Standard Service Summary report' shows 59270 answers viewed
The custom created report 'Overzicht aantal bekeken antwoorden kennisbank via de website' shows 58942 answers viewed

So there is a delta of 328 views

Further: 
The 'Standard Service Summary report' is based on the stats table
The custom report is based on the ans_stats table

And:
The stats table is being fed by the 'dataminer' utility
The ans_stats table is being fed by the 'DQA: (Delayed Query Aggregator)' utility - containing end-user data of max. 4 hours old