Engine RPMs - Converter not locking up?

[svxbrick]

Checked on the way to/from work today and noticed that the rpm dropped from 2600 to 2300 at 70 mph after driving about 5 miles on the freeway (8 to 10 miles total). When it was turning 2700 the revs would go up when I gently pressed on the gas but the speed didn't (also dropped about 500 when I let up). At 2300 the speed went up with the revs so it appears that it was locked up at that point.

The outside air temp was around 30 on the way to work and 50 on the way home but I would think the tranny would be warm enough before going 8-10 miles with 5 at freeway speed.

Does the transmission control module have to re-learn after changing the tranny?