Oil vs. coolant temperature

A question for anyone here who knows about engine cooling: I have a 2003 BMW 325Ci. I recently installed an aftermarket oil temperature gauge: manufactured by VDO, and the sender is attached to the oil filter housing. I've noticed the following behavior:

In cold weather, say ten degrees fahrenheit, the reading on the gauge barely gets above 120F on the highway. Maybe it'll make it up to 140F at the most, in mildly warmer weather. On slower roads and in traffic (and in the summer, on the highways), it heats up a little more, maybe to 150 or 160. Only when I'm completely stopped, or inching along in stop-and-go traffic, does it make it up to around 200.

I have verified (with an infrared thermometer) that the temperature the gauge is reporting is approximately the same as the temperature on the outside of the sensor housing. Using the instrument panel diagnostics, I've verified that the engine coolant temperature also warms up quite quickly to around 200F and stays within a few degrees of that as well, regardless of what kind of driving I'm doing.

Does this sound normal to you? Today, for instance, I drove 100 miles from Hartford to Boston, at 80 mph in 35F weather. The coolant temperature stayed around 200F, as always, and the oil temperature displayed on the gauge as 140F for essentially the whole trip.

This doesn't make any sense to me: it says that, after driving 100 miles at 80 mph, if I come to a tollbooth, the engine is not sufficiently warm enough for me to rev the engine to redline when accelerating away. That does not seem right. I certainly hope it's not right, because I do that several times every time I make this trip.

Any opinions?

I realize that the oil takes a lot longer to warm up than the coolant, but at equilibrium I would expect the opposite of this situation to be true: the coolant has 80 mph of cool air rushing over the entire radiator to cool it, while the oil only has whatever turbulent flow sneaks past the radiator and buffets against the engine block. Logically, the coolant should run cooler, not the oil