AAARRRGGHH! KEEP YOUR MOUTH SHUT!
Oh sweet jesus, don't say a goldanged thing. You'll screw up a friendship, mess up your licensing, and in general you'll die of embarrasment.
Whatever you think you're reading, you are WRONG! Keep telling yourself this right up until she puts her hand down your pants, and then, and ONLY THEN, start to wonder whether or not your original thoughts were correct.
Never say anything. I swear, I have a friend who has made this mistake MANY TIMES. I beg of you, just SHUT UP and finish your cert work, then pay them, thank her quietly, and leave.