If you notice that you are being locked out of your Gmail account, this is caused when your Gmail server is reporting that bandwidth to your Gmail account is being throttled.
This is an pretty rare phenomenon. The throttling should clear up in the next 24 hours.
Here are some google engineers on this topic: http://www.google.je/
What is happening:
1. Your account is hitting the download bandwidth limits, which is the maximum amount you can download from your account in 24 hours.
2. The usage is grouped into buckets, so as time goes, some of the old usage expires, and new usage is available, so you may have access in as little as an hour, but it may not be much.
SaneBox uses almost no bandwidth given that we only look at the envelopes and never the actual body of the email and we only look at each envelope once. Usually you go over the bandwidth when you start up or sync an aggressive mail client like Mail.app or Thunderbird and you have a lot of email.
You might consider changing the settings of the client to be less aggressive. Perhaps have the client avoid downloading attachments.