Because others had speculated about this whole name check business, I specifically asked my USCIS interviewer whether this had been completed for me. He said that one won't even receive an interview letter until this has been done. Also, Chi-Guy, there's been nothing especially fast about your interview progress. It's moved at the average speed for Chicago until the interview and substantially slower than average after that.
It looks like both of us may be going through a second round of name checks, perhaps after they had a chance to collect additional detail about my citations, your arrest, etc. My theory is they don't have much information on this until you actually provide it to them in the interviews. Only then, do they launch some sort of effort to confirm things with local police departments.
Initially, when I was unable to find my old traffic tickets, I had contacted local police departments for records. In some cases, it took over six weeks for them to respond that they did not even retain the information! If the FBI is trying to do the same, it would explain the current long wait.
Incidentally, if traffic citations cause such tremendous delay in the process, this may be another reason not to indicate them on the application. From loking at various discussions, many seem to have speedily and successfully achieved citizenship without declaring them.