" I don't count"
I. Freakin. Love. This. Scene.
Why?
I'll tell you.
Look how confused he looks when she says "I don't count". He's confused because she does count! She does and she always has. He's suprised she hasn't figured it out yet. This tells us:
1) He thinks Molly is smart (respects her), so he is confused she hasn't firgured it out.
2) If she could have figured it out, then it means he would be leaving clues
and 3) Count is Sherlock's way of saying love