Question about my RTB

So I was wondering I usually take my RTB Lord Pistachio out of his cage for a half hour a day usually around 5pm to 6pm out here in southern calif, so he gets some good sunlight soaking and I let him crawl around on the grass, well I pretty much let him crawl around where ever he wants to go (please note I am supervising him to make sure he doesnt get near any holes, brush, trees or shrubs, gross things other animals leave as well as to protect him from any potential predators or harm) I am usually only 4 feet away from him at all times.
Anyhow I am assuming that this sunlight is good for him, Yes? He looks so pretty in the sun. I will have to take some pics tonight.

Not sure it's 'good' for him. He probably doesn't mind it. As long as he's not overheating out there.

Well the fresh air and sunlight can't particularily hurt him as long as you are really careful about supervising his outtings. If he seems at all stressed by it, then of course, you'd want to adjust things but they don't stress nearly as easily as ball pythons. Do make sure whatever grass he's on hasn't been treated for weeds, had fertilizer put on it or is near or under trees that have been sprayed for anything.

We were so lucky when we had the big female boa that we had a completely screened in porch. She could go out there and exercise, get fresh air and indirect sunlight, watch the squirrels in the yard but was under control (she was over 6 feet so loose in the yard wasn't a great idea due to her size and our neighbours freaking out).

its not the noontime sun so its not hot ,the temp is usually cooling off as its evening. when I pick him up he is cool/warm so I know he isnt geting hot. He seems to like it. I was wondering if he gets vitamins and other good things from the sun. I never take him out if the heat is oppressive or making me sweat .

my snake is just under 6 feet, he is so calm just crawling around slowly flicking his tongue. stopping every so often to "sniff the air" then crawling again, sometimes he crawl right into my lap. He has marking on his mouth part near where his tongue comes out and it almost looks like he is smiling, he is so cute. heh heh

I'm not 100% about this... But I'm pretty sure that snakes don't create Vitamin D in their skin from the sun the same way humans do, which is what I think you're referring to. In fact if they did captivity period would probably be pretty miserable for them.

Edit: I did a few minutes of research and it looks like they can synthesize it from UV light, but even if they're not exposed to it, they can get it from their prey.