Thank you for your response.
As you suggested, I checked the time stamp and it remains the same. It looks like the error only happens when I use the Cache Tester in Dashboard.
The blog site is working fine with Super Cache (have not found any problems yet).
Is that your experience with this error as well? That the error is contained in the Cache Tester but does not effect blog site performance?
Thank you very much for your help and for this nice Plug-In.
