Honestly he hadn't expected to actually hit Zevran, but he did, and for a moment Sam isn't sure quite what to do. At least until there's a shout and he sees Zevran looking down at him, readying a snowball. "Well shit-"

Running out into the field would only give the man an open shot at his back, but standing there would certainly get him hit in the head. So Sam does the best thing he can figure to do, hide up against the base of the tree where the branches are in Zevran's way from his current position.