'gurgling' sound when turning crank to tdc

So I went to check the valves on my new brp today and had the rocker covers off, plug out turning the flywheel counter clockwise to get to tdc... my plug was BLACK so I know i'll have to do some tuning... but when I started to turn I heard gurgling and bubbling sounds... I have never heard this on my rmz when doing valves so it alarmed me a little bit. Also, my straw (to help find tdc) came up covered in black soot... I tried to push it back in to scrape some off the piston and I got a good bit off, meaning there is a pretty solid layer of gunk on the piston. Something I should pull the head and check out? Also, is the gurgling noise indicitive of a problem or is that normal?

Gurgling is normal, it is the oil that has leaked from the oil tank in the frame down to the engine which is why they tell you to run the engine before checking the dipstick.

Black on the piston is pretty normal for an engine. Wet black would be an indication of a rich jetting mixture. Black to tan with slightly scaled appearance is an ideal mixture.

Thanks, just hadn't heard it on my rmz which is the only 4stroke I've owned.... I'm used to black pistons coming from smoker land too... Just wanted to make sure