Good teams make good plays. The Yankees are a good team full of dangerous hitters; they managed to take one game (the game we all probably assumed would be a loss going in), built a late rally mostly against a guy who just came up from AAA in another game, and had another late rally bested by defense. The Astros are also a good team and took three out of four against one of the best teams in baseball this season, including torching one of the Yankees' best pitchers this season.
Not trying to explain away Sunday's bullpen shenanigans, but I'm not overly worried.