HOUSTON — Maybe it’s presumptive to think of it as a potential problem since planning for postseason pitching hasn’t really been a consideration since Lou Piniella was still wearing a uniform and gas was around $1.65 a gallon. And the idea of worrying about a potential matchup with the Houston Astros in the divisional or championship rounds of the playoffs seems a bit irrational considering the Mariners haven’t been there since 2001. It’s also not an impossibility if the Mariners make the postseason and win their three-game wild card series. Their starting pitching is that good … well, sometim…