If you're talking about the LFS it's most likely a cyanobacteria or blue/green algae and yes it's presence is a good indication you are over watering. I get it in my other carnivorous plant pots all the time but hardly ever in my nep pots. It could also be the sphagnum coming back to life but I doubt that's happening if it hasn't been long since you re-potted it.

Which days do you water them?

The LFS on the top of my heliamphora pots is also turning green. I had also just noticed the green color, and thought it looked liked the LFS was coming back to life (although it's hard to believe). I'm not worried about whether this is a sign of over-watering, but if it is cyanobacteria or blue/green algae, can this be harmful to the CPs?

I water when the media gets dry on top or when my live moss starts looking lighter in color.

No it won't harm the plants unless it actually out grows some pygmy sundews which will smother them.

Thanks Taz.

what does LFS stand for?

long fibered sphagnum.