Try centering using the method described above, it takes only moments and anyone with the right size allen wrench can do it. Just don't touch the rotor with your hands, wear gloves just in case.
If that doesn't change anything take it in to have the rotor trued, it's a simple process which they should only charge you about $10 to do.
You can true your rotor at home with an adjustable wrench; however, I tried this once with terrible results. My wrench had some oil residue on it (like many of my tools) and it contaminated my brake pads. That was a worse outcome than just taking it in and paying the mechanic the $10 do use the proper tool. If you do attempt to true the rotor at home, make sure to clean your tools first with high concentration isopropyl alcohol. Good luck and welcome to the wonders of the disc brake!