1998 Hatch overheat.

After a flat out run from Kingston to Toronto (250km), I had the car
idling in the driveway for several minuits to check things over (Can't
be too careful with a beater that's got 280,000km and still running
with all the original components under the hood). To my surprise, after
idling in the driving for several minuets, the engine temperature gage
starting rising. Which was very surprising, cause that was the first
time I've ever seen the temp gage move from it's 1/3 mark. I checked
under the hood and the reservoir was at the max level. The radiator and
in/out house were all warm to the touch (warm enough for me to grab
hold of them without burning...which is surprising since the car was
going over 100mph back from Kingston). It only took me less then a min
to do all the checking cause I was in a bit of panic. I went back into
the car, the heater was turned off and all the way into the cold
position. I moved the leaver all the way into the hot position and
blasted the heat. Very hot air started coming out the heater and the
temperature gage dropped back into its normal 1/3 position. It's been
several days since that episode and I haven't encountered anymore weird
problem with my cooling system.

My guess is, after driving the vehicle hard it cooled off rapidly after
exiting the highway and idling in the driveway, somehow air was
introduced in the cooling system, there was some kind of blockage and
when I turned on the heater, the blockage cleared up. If so, I won't
worry about it. But, I'd like to here if you Guru's got any
suggestion for preventative maintenance.

Pars