As long as you didn't beat the snot out of the Van on the way up to 85
mph every time you got there I don't think you have done any harm.
An engine that runs at a constant speed, as if it was on a governor, as
if were on a hydraulic pump, or heavy machinery all day every day will
out last any engine that is handling various load conditions up and down
with the speed as a vehicle in the city would every day.
Don't worry about a thing.
Consistency on the road is much better for any engine than road racing
from stop light to stop light.
Like I mentioned before, if your worried about all the fear factor's
that were brought up in prior messages regarding valve train damage due
to bigger RPM's and heat that goes along with it, drop some lubrication
into the gas to keep things cooler and oiled up upstairs.

RC