Nothing to worry about, and nothing having to do with sex, either, at this
young age. Even adult men regularly get erections
in their sleep that don't have anything to do with wet dreams or sexy stuff. Margy, all erections are spontaneous, he wouldn't "copy" another kid by getting an erection. (If guys were that in control of erections, the Viagra people would be out of business.) Or are you asking if he handles his penis to give himself one?