Green Moss? In My Soil?

I have started 3 plants, for now they are in 3 different plastic cups, i watered last night and everything was fine but when i awoke today there was a green moss like substance on the side of the cup where it meets with the soil. Also there were a few very small green specs of this mossy substance throughout the soil. Is this something I should be concerned with, or that I need to take care of right away? Also is this moss?
Thanks

stop watering so heavy an so often..thats whats causing the green buildup..

how much is a good healthy amount of water?

the plants will tell you...listin to your babies...

or wait untill the soil becomes dry on the top but still moist a little into the soil...a good way to do this is with your finger tips...stick them into the soil about an inch if its real wet wait if its starting to dry but still damp add more...