Arrived at the gate in SFO for my flight to LAX. Noticed that I had been upgraded to first. Went up to the counter to inquire. The agent told me I was only waitlisted and definitely would not clear with a definite negative happy tone in her voice. Did not argue or say anything. As I was settling into my E+ seat guess who comes on board and gives my first class upgrade, she said nothing, just handed it to me. In fact I was the only one upgraded, so agents are not always right.