2000 2.7 mt boxy cooling system problem?

[rdass623]

on Saturday I was flagged down and told my car was leaking, so I pulled over and saw coolant leaking from the passenger rear side of the car, a bit inside of the rear wheel near the pass side drain for the runoff from the top. the carpet was slightly damp in the trunk near the expansion tank. looks like a time to replace the tan. this happened close to home so i refilled the tank and slowly limped home staring in the rear view mirror for a coolant trail and at the temp gauge, stopping once to refill the tank. i arrived home and parked the car Sunday. today i pulled the carpet in the trunk and engine cover, filled up the coolant tank, purged off the air from the system, refilled the tank, and let it idle with the a/c running for an hour..... nothing is leaking now. drove it around the neighborhood for a short while, still nothing! does anyone have any ideas? my car was purchased six weeks ago, with 50K miles, so i am not really sure of it's history, but everything seems to be working as it should now..