I got home from work and, since I don't have a garage with lighting, had limited time to mess with the bike. I did take out and clean the air filter though. How dirty would it have to be to interfere with the acceleration?
When I took the air filter out there were bits of grass, dried leaves and dirt all over it. My original thought was to use the electric tire pump to blow the dirt/grass/junk off but it didn't have enough oomph. So I used a vacuum cleaner to clean it and it darn near changed colors. So is that dirty enough to cause issues?
Unfortunately, the bolts for the seat were a bit awkward so the regular wrenches I bought didn't work. I had to make a side trip to Home Depot to get a socket wrench to take the seat off. By the time I was done the sun was setting so no more tinkering -- didn't have time to mess with the spark plugs.
After that, and checking the oil levels, I think the dealership lied about doing the 600mi service.

I hope this doesn't shorten the bikes lifespan...