Jason,
My '82 diesel's gauge needle moved from below the light to above the
light with a t-stat change so yes there can be quite a difference from
t-stat to t-stat.  In my case, I wanted the higher temp.  My diesel
seems to run quite fine at the higher temp.
As long as it does not continue to rise, I would not worry too much.
Mike Pidcoe
'82 diesel
'86 syncro (suby powered)
'74 Thing
'87 Intermeccanica