If Loki hadn't been busy teleporting this way and that way in order to avoid the veritable onslaught of snowballs coming his way, he might very well have patted himself on the back for a job well done. America hadn't laughed or let loose lately and -- well. Apparently they were friends enough where that was something that Loki was concerned about. So had he planned this? Maybe yes.
Which was maybe maybe the reason he let America get a few snowball hits in.
He was grinning wide and energetic himself when she landed, hands on his hips (because no matter what he was doing, Loki was still regal). "My schedule is clear," he said, as if that was the only thing he was concerned about when it came to a snowball battle.