without a pic it's hard to say for sure, if you've a decent camera then please do get a pic for us, although to be totally honest about it, not everyone has a camera capable of getting good enough shots of tiny little worms like this and most of the time the pics aren't good enough to confirm the ID. This is why generally it's best for you to look up pics on the internet which will generally be good quality and compare them to what you are seeing.
if they are planaria then they are hamrless so you don't need to worry about them.