mysterious coolant?

i have a 98 Grand Am with the 3.1-L engine. i was recently low on coolant ( the low coolant light came on), so i refilled it, and about a week later i was low again (during this whole time the engine never did run hot). I had notcied something leaking onto the ground, which was coolant, so i figured my water pump was going bad, because i mean hey, it does have 100k miles on it. i just refilled it with water until i had a more convenient time to go get it looked at. but since then, i noticed some leakage on the ground once (which was coolant), other than that, nothing, and the coolant is not low and the engine is running fine. can anybody tell me whats going on? and should i be worried?

Having your cooling system pressure tested will tell the story...Most common place for a coolant leak on that engine is the intake gasket