Not entirely. As I understand it, that re-licensing occurred when a member of the Doom community emailed John Carmack asking him if he would be willing to release the source under the GPL. He said no problem, but there was never an official source drop with the updated license from Id Software. Carmack's email is all there is, and there's some ambiguity over whether he had the legal right to unilaterally re-license it. This official release puts its GPL status on more solid ground.