My van shows an above normal temperature.  When I bought the van 6 months ago the needle of the temperature gauge was always just below the LED.  Several weeks ago the needle suddenly climbed just above the LED.  I checked the coolant overflow reservoir and found it empty.  I filled it up with about one quart of water.  The coolant level has been ok since then but the gauge still shows an above normal reading.  Today during warm wetter and slow traffic the needle went even higher, about halfway between the LED and the end of the scale.  The radiator fan came on a few times also. 
Does anybody have an idea what's going on ?
 
Many TIA,
Peter
90 Syncro Westy
SF, CA