CPS is also quite used to getting retaliatory/innaccurate reports, so don't get too freaked out! You're a good mom and Nicholas is very loved and well-cared for, so I really don't think you have anything to worry about. The officer could see that, and his superior wasn't there and simply covering asses on the off chance the reporting officer was wrong in his assessment. Just out of curiosity, how old is Nicholas? When I was ten I used to babysit other kids, but it's a different world these days.
(Btw, when Tori was nearly three her daycare threatened to call CPS on us because she had bruises all over and a pretty dramatic new one on her chest. We were freaked out, as she had been sick with this intractable ear infection for nearly four months, and now every time she bumped aganst something there was a new bruise, but a trip to the docs finally cleared it all up: she had been taking ibuprofen for the ear pain and it was causing the bruising, and the chest bruise had actually been incurred that day at the daycare when another kid poked her with a drum stick. The office hadn't bothered to check the daily incident report.
. The ear infection is what eventually damaged her hearing. Anyway, I totally understand how you feel, but be glad that at least they do check on reports!)