Do OAuth access tokens expire?

[Jayesh Salvi]

Hi,

Some of my users and myself noticed that our Google Reader queries started returning 401 client error. I was using OAuth. I logged out and logged back in again using OAuth and all queries started working again.

Till now I was under the impression that OAuth access tokens and secrets never expire, unless user goes to service provider's page and blocks the access. Is that incorrect?

If there is any chance that the tokens might expire what is the timeout for Google reader?

Thanks.
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Jayesh