Heat related binding in steering problem

[TWOOD]

OK, I have had my CRII completed and on the road since '08 and I have experienced an intermittent binding in the steering while driving.
It comes and goes and I believe it occurs only when the engine is hot and the car is moving at slower speeds.
If everything cools, is disappears.
If I drive it at freeway speed for a period of time (lots of air moving through engine compartment), it disappears.
It can be felt in the steering wheel when making very slight adjustments while driving. Kind of a catch and then a release and a catch and then a release.
I am thinking that maybe the header is heating up the steering column rod and causing it to expand and lengthen. The clearance is only about ½ inch.
Could that cause this symptom?
Rack and Pinion is from Flaming River and column is from Ididit.
I believe my kit was one of the very last ones delivered from CII prior to Don Scott's misfortunes.
p.s. phasing of the universal joints does not seem to be a cause since no binding occurs when cold.
Opinions & Thought are appreciated!
Thanks to all for reading and or replying.