If you find only males on shallow cover they're either making a nest or guarding one. If both male & female fish are on a piece of cover, then they're likely engaged in the spawning process. Females are not wont to drop all their eggs in one nest, but will retreat to a piece of cover some ways off from the nesting area & then come to visit any number of nests they find suitable over the course of several days or as long as it takes to drop their clutch ... if conditions remain tolerable.

Even a limbless trunk is suitable cover, as well as a possible current break.

The creek may or may not be at a higher temp, unless it has access to a lot of sunlight along its path. But you are quite right to consider checking it out, if only to find out if the water is indeed warmer.

Luck2ya on your continuing adventures !!