Need help with my 2001 Jeep Grand Cherokee Laredo!?

I recently bought a 2001 Jeep Grand Cherokee Laredo. Its runs perfectly and is in great condition. It has a little over 110,000 miles on it. About a few days ago the coolant low light came on, and had it refilled. Two days later the light came back on. I just figured the mechanic didn't pump the air out when he refilled the coolant. Today I looked in the engine and the oil is above the normal levels and the coolant seems lower. There has been no leakage. What could the problem be?