2000 Toyota Camry help!!!!!

I just bought a 2000 toyota camry last week...I had it checked out by my mechanic and he said it was in good shape and there wasn't anything wrong with it...I noticed a couple of days ago that when I first turn on the car the check engine light, battery light and another light that looks like water dripping out of something light up, they dont stay lit but they light up briefly when the car is turned on....now I admit I know absolutely nothing about cars and I dont know if this is normal or if there is something wrong with my...it has been driving fine and there is nothing else to make me supsect something is wrong...