Looking at the last five minutes, at 14:23 he sort of falls awkwardly into the boards. Gets back up and looks fine. Malkin hits him a few seconds later, doesn't look like anything special. 16:35 Kunitz hits him into the boards, also pretty run-of-the-mill. If there was a 'puck to the chest' (or something else), it must have happened in the first 15. Or maybe an old injury that finally caught up with him?