Eric Feron, a Google AdWords Community Manager, posted on Saturday at the Google AdWords Help forums that a bug may have impacted your ads from displaying on Saturday.

In fact, it was not just any Saturday – it was one of the busiest and most successful Black Friday/ Cyber Monday weekends for online shopping ever. And it is possible that your Google AdWords ads were not showing because of a payment bug.

Eric from Google explained:

It seems that the issue was addressed quickly but I am not sure how long it lasted. Was it a few minutes, hours, half the day? I am currently not sure.

It seems the issue started for some on Friday and some are still saying the issue is not resolved for them. I am not sure if this bug is related to those people or not.

Forum discussion at Google AdWords Help.