2003 Infiniti G35 Sedan hard start?

I have a 2003 Infiniti G35 Sedan with about 79k on it. Everything was runningly perfectly smoothly but now all of a sudden when I go to start the car, I turn the key and it makes the normal cranking sound, but it does this and the engine doesn't catch on and actually start for about 10 seconds of holding the key down! it used to be once and a while, now its every single time I leave it off for more than about 20 minutes. Once the engine has started, everything runs perfectly normal. Any ideas? Greatly appreciated! Would a tune-up solve my problem?