James needed no more invitation than that, and he was swinging open the door and letting himself in.
Remus's location was hardly some great mystery. James had been thinking he'd probably be sprawled out on the couch, but seeing as to how Remus wasn't in immediate eye-shot, he had to be in his bedroom. Not mystifying, but it was hard for James to figure how Remus had mustered the will to get beyond the living room. Sirius, most likely, James reckoned.
"Hey there, Moons," he smiled, leaning up against the door frame. "You up for company, or are you still pining for beauty sleep?"
It was James's constant effort to trivialise Remus's furry little problem-- because it was trivial to James. Oh, sure, he knew it was a big fucking deal, and that it weight enormously on Remus, but that was the point. It didn't make an ounce of difference to James whether Remus was a werewolf or not. So he liked to treat it with the same level of seriousness that applied to, say, Peter's inability to get a date.
Plus, if Remus said he was up for company, he'd only have himself to blame for not turning James away.