I would not worry either. I had a man like that once. He just prolonged for me, and then after that it took forever to "finish" but, he was by far my favorite!! There is nothing sexier than a man who is there to please you, and who doesn't make excuses like "well, it has been a while"
just relax and enjoy. You may have to work a little harder and take some more time to finish him, but at least you know you are guaranteed yours!