So I recently bought an 08 A4 3.2 Quattro automatic with 50k miles and it's been completely amazing so far, the only thing that worries me is that whenever I start the car after leaving it for more than a few hours (say, overnight) it takes forever to start, like an old car in the dead of winter. I have noticed that if I tap the gas at all while it's struggling to start (which could take 5-10 seconds if I left it alone) it springs to life.

Is this something I should be worried about/a symptom of anything in particular? I'm using 93 octane gas...