it could just be more discharge as that's normal, but if there's quite a lot of it it could be waters leaking - think they advise you to pop a pad on and if it's wet an hour later it could be waters. If it is it should be odourless.
I've had this since 33wks (now 39). I went to hospital to get checked as they wanted to make sure it wasn't my waters that had started to 'leak'. I was told it was just watery discharge and it can happen to some women, and sometimes it can feel like water has leaked but nothing to worry about. Since my 1st visit to hospital, I have been 4 times to get checked because it feels that much like im leaking but still the same answer! a couple of times I've even had a 'gush' of it which makes you think its your waters but it wasn't!
If its more water than discharge then give the mw a call and they may ask you to go in just to get it checked, doesn't take long at all. You're never wasting anyone's time, they would rather you go in to get checked rather than worry over what could be nothing.