STC makes the most important point. Don't inadvertently cause him to be ashamed of the act. The repercussions of that could last a long long time. I remember things that were said to me (in a more hurtful vein), by my stepfather, and I think I carried them with my self image for far too long, in such tiny subtle ways bearing some sort of imaginary shame... Wow.
Choose (your words) wisely. I'm sure it'll all be just fine.
