text: In general, elevation data is not stored in OSM other than at specific peaks and other points, so the Gaia may well use its own (SRTM?) elevation data.
  I don't see any specific waypoints or POIs particularly close to here, and the John Muir Trail is stored without elevation data, so far as I see.
  If your error is located within a few hundred metres of this marker, there is nothing I see in OSM data with elevation.  If your `little earlier' is further removed, I have not looked, but the pass appears nearby on the Cycle Map display with contour lines (not part of OSM, but an overlay from SRTM elevation data).
  I hope that may explain things, as I see them.  No guarantees.