For certain PostGIS layers, the estimated extent in the X-axis is badly exaggerated toward zero in one dimension.. e.g. I am building California data, with no zero values, and I see 0.6 degrees as max-x on several layers.
I do not know for certain what is causing this, but it appears that Geoserver is issuing ST_Estimated_Extent() in the 'new Layer' process.. PostGIS 2.1 responds in the log with a warning:
WARNING: ST_Estimated_Extent signature was deprecated in 2.1.0. Please use ST_EstimatedExtent
CONTEXT: SQL function "st_estimated_extent" during startup