Rick,
As long as your car can handle pulling decent hills in hot weather don't worry about it. You likely have a bit of air in the system that will probably work it's way out. There are so many places that things like the sending units, gauges, thermostats, etc. can be a little bit off that you can drive yourself nuts trying to get your car to be just like everyone else's. Ultimately, if it's not overheating in hot weather under heavy load you have no problem. Unlike gassers that can get preignition problems if they run a bit on the hot side, diesels actually like it.

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LRG
1987 300D Turbo 175K
2006 Toyota Prius, efficent but no soul
1985 300 TDT(130K miles of trouble free motoring)now sold