At 60K, just go ahead and change the plugs. They are the Bosch Platinum +4 plugs so they don't have to be gapped when you put them in, but like cyclocross said, the gap can change over a long period of time.
They're easy to get to, right behind the rear wheels.
Great to hear it seems to have gone away. If it comes back and you do all of the cheap fixes and still have the problem, you may want to check the coils. There's a separate coil on each plug so if one goes out the engine still starts but runs rough because it's missing a cylinder. Missing can be dangerous because the gas runs down the cats instead of burning in the cylinder. Probably not a problem with only 1 out, but more could be bad. I think they're about $55 each so you could get one and trade it out one every couple of days until it goes away. Just another cheap way to test before getting to the expensive sensors.
