Users may have noticed in some cases that a records 'Updated' (sys_updated_on) date/time is slightly different (usually a few seconds) than its Audit records 'Update time' (update_time).  This is because the 'Updated' field is the date/time of the beginning of the transaction (when the Save/Update button is clicked) and the Audits 'Update time' is when the transaction completes.  In most cases transactions complete within the same second so there usually is not a discrepancy. However in some cases, there maybe many business rules that can take an extra couple seconds to complete so a user might see a difference in time between the updated field and what the audit history shows.  This behavior is by design.