Google has changed the way keyword quality score is reported in AdWords. The change only affects the numbers viewed in AdWords. There is no effect on the algorithm of calculating quality score or the ad serving such as how auction-time quality signals affect Ad Rank and CPC.
Clarifying the reason for the update, Google has said that the change would allow them to simplify a few core system, with focus on improving reporting accuracy for keywords with traffic.
One of the changes to the reporting is that keywords will default to a reported score of 6 before receiving traffic. When enough impressions accumulate, scores will update.
AdWords quality score reporting was last updated in July 2013.Google Announces Change in AdWords Quality Score Reporting!,