Nipple discharge (TMI?)

So I'm about 21 weeks along and I noticed last night two little dots of wetness on my shirt near my nipples. I've since started paying more attention to my nipples activity and have conclude that yes they are leaking somewhat, though it seems very little at a time. Usually just enough for my nipple to feel a little wet, but not enough for anything to rub off on my finger. Occasionally I have rubbed off a tiny drop of clear liquid though. It seems possible it's happening more on the left side than the right.

Is it normal to be leaking discharge this early in pregnancy without any nipple pressure or stimulation? Should I do anything about it or just let it happen as it is?

I've heard that if you express the colostrum by yourself or too early it can make your milk come in too early is this true? Should I be concerned my nipples are doing this on their own, or just avoid messing with them?