Yesterday, Google accidentally sent out an email to AdWords advertisers who cancelled their ads, telling them their ads are now running.
If you received an email from Google saying "Your ads are now running" regarding your AdWords account, disregard it, it was a bug.
AdWords representative, Bindu, said:
AdWords advertisers who canceled their account or who are now no longer responsible for the payment to the account received the email: "Your ads are now running." This email is not accurate.
If the account was canceled, it will remain in a canceled state and ads will not serve. If you are no longer responsible to pay for the account, you may ignore the message.
Our engineers are now working on solving this issue. Sorry for any inconvenience.
I personally did not receive this email, did you?
Forum discussion at Google AdWords Help.