Bad Thermostat?

[ricematthews]

The car is a '98 A4 Avant Q 30v 2.8, purchased by me in November 2001.
Usually when I drive the car, the water temp gauge settles quickly at the
mid point and stays there (even in the winter).
Lately, there have been a few occasions when I have noticed that the temp
gauge doesn't get that far - by a long shot - in 85-95 degree weather.
On one particular occasion, I had a brief drive on the highway (5-10 miles @
60-70 mph) and afterwards it was pinned at the "cold" position.
On another occasion, I drove over back roads (not stop & go, but not highway
@ 35-45 mph) and it seemed to have difficulty making it to 1/4 of the way
between cold & hot.
The car has recently had the thermostat replaced.
Is this normal for these cars, or is it likely that I have a bad thermostat
(i.e. sticking open)?
Thanks!
-Mark Rice