Over the weekend, Google AdWords advertisers began to worry when their quality scores began dropping. A WebmasterWorld thread has some of the advertisers freaking out.

One said:

Whatever it was, it last a day or so and the quality score numbers went back to normal.

I am a bit surprised. Back in late July, Google sent out a warning that quality scores should drop in the future and it is nothing to be worried about. I assume it was this but I was wrong because the quality score numbers went back to normal.

Here was another report from an advertiser when his quality score dropped during the bug:

Forum discussion at WebmasterWorld.