I'm no expert on business diplomacy but my own take on this would be to drop him a very neutral e-mail. Depending on your relationship and on his personality. "I noticed that the keywords were not 100% effective on this job. Is it too late to review?"

How would that sit with you? He will probably ignore the comment but you can feel that you've covered your responsibility and put the ball firmly in his court. Then you let it go, get on with your life, and act surprised if he raises it in future. "oh that job? I'd forgotten about it already but do let me know if I can be of any help in future".

I'm not confident enough about successful diplomacy to put this forward as general "advice" but I've been in some similar situations and work relations exist in the context of long term relationships in my experience. Therefore I behave as I feel comfortable, which is to step back in my own driven personality and keep potential conflict to a minimum.