The perturbed angular correlation method was employed to study the lattice environment of In implanted into GaN. It was found, after annealing the implantation induced damage, that 65% of the implanted atoms were situated in regular undisturbed Ga lattice sites. The remaining fraction showed an unusual behavior insofar as its lattice surroundings changed reversibly from undisturbed at temperatures above 600 K to strongly disturbed at low temperatures.