Yeah that'll be the hops breaking out of the bag as they swelled up in the wort. Don't worry about it, it will sink back into the beer and settle on the bottom of the fermenter as the yeast activity subsides. CO2 bubbles coming out of the fermenting beer will give yeast cells (brown to browny white stuff) and hop particles a little ride up to the surface.
Yes it does settle out. The first time I used hops bags I assumed they would keep all the material in but that's not the case. But it doesn't affect the quality of the final product in any way. Sometimes too you can see a touch of green in the yeast sediment @ the bottom of the bottle.