2001 honda civic lx 4dr. Temperature gauge went up to hot maximum for about 5 minutes then went back down to normal position. Why?

Driving only 15 minutes at 35 mph when this happened on temp gauge what seems to be the problem? This is the first time this occurred.

Either sticking thermostat or faulty temp gauge.

Make sure that you do not need to add water/ coolant to the radiator.

Have you even checked the coolant level to see if it's low?

Check the coolant level. If it is low, check for a leak. If the coolant level is ok, bleed the coolant and drive to see if the issue goes away. See a garage if the issue does not go away.