surprise surprise

my boss communicated 2009 comp. Well I know my bonus would not be bad since the rating was quite high. so I did not pay much attention to what is on that piece of paper. simply said thank you to my boss. Later when I took a look at what was on the paper, to my surprise, I am granted a long-term retention incentive for 2010. Based on policy, I am not qualified for this retention bonus. this is an exception. I don't know what to say. should I talk with boss again to let him know that I appreciate this? It is kinda awkward since it has been a few days.