Spontaneous orgasm?

Ok, so this literally just happened and we’re both very confused and he’s kinda freaking out.

So my husband (he’s 27) works nights, he usually just smokes pot to help him sleep during the day but some days (today being one of them) he’ll take a sleep aid as well, store brand unisom.

Anyway, he got up tonight at his usual time and ate dinner and got ready for work. He’s more tired than usual, though, because we had some errands and our daughters’ had their therapy appointment today, so he went to bed later than normal, but he did get about 6.5 hours of sleep.

I packed his lunch for him and sent him on his way with well wishes and he said he’d text me when he got to work so I know he made it safe (I worry a lot with him driving at night) and off he goes. About 10 minutes goes by and there’s frantic knocking at the front door, which I open and find him standing there. He very hurriedly opened the screen door and barged in, clearly panicking. And he looks at me and says “babe, something really weird just happened.” He’s not at all amused or humored when he says this, he’s very anxious and it makes me worry. So I ask him what happened and if he’s ok and he responds “yea, I’m ok. But I just had an orgasm out of nowhere. I was driving and I realized I had forgotten my phone and my anxiety got really high all of a sudden and I started feeling stressed because now I have to turn around and I’m worried I’m gonna be late for work and all of a sudden I had an orgasm. This has never happened before! I don’t know what’s wrong! Is this bad? What can cause this?” I told him I don’t know what causes it and I don’t think it is a bad thing, because honestly, what harm comes from an orgasm? Yes it’s odd and I have no clue what could have caused it. I helped him get undressed and cleaned up and ready for work again, all while trying to reassure him.

Now, I feel like I should include the info that we haven’t had sex in almost a month for a couple of reasons.

1 reason being I’m 33 weeks pregnant with our baby and it makes him very nervous having sex (this is his first time with pregnancy and I went into preterm labor 2 weeks ago so he’s even more nervous) and 2. He has hsv2 and is getting over an outbreak and just finished his first ever cycle of valtrex (he just got insurance through his work and can afford the medicine now) and he’s VERY strict with our sex life until his outbreak has been clear for at least a week (which isn’t a bad thing and so far, I don’t have it and I get tested regularly just to make sure)

that being said, he has been taking care of himself pretty much on a daily basis. It’s like the scenario “tell them they can’t have it and then they want it more” kinda deal.

I should also mention that he doesn’t have a very high sex drive at all and I’m VERY sexual so it’s a bit of a struggle in our marriage and with his work he’s exhausted a lot and masturbating is a “quick effortless” release. This doesn’t bother me at all because I do it as well for a quick fix.

So, when he walked in the door absolutely freaked out by this, it has me concerned too. I’ve had orgasms in my sleep, quite frequently actually. But never spontaneous while I’m awake. And he’s never in his life experienced anything like this, even as a teen. So now he’s thinking there’s something wrong with him and I don’t want him thinking that at all because he doesn’t have the greatest self esteem when it comes to his “manhood” (despite how much I LOVE it and tell him all the time)

Can anyone help us out with experiences with this or possible causes? Anything? I just don’t want this to eat away at him and bring him down.