Do you refrigerate a PB&J sandwich when taking for lunch?

Noooo. I take PB&J to work and on day long hikes because it doesn't need to be kept cold. I grew up using homemade jelly and now I use either homemade or a commercial brand. So I don't think that's an issue.

I make my sandwiches (yes, 2!) in the morning not the night before. I think the bread gets stale and the jelly seeps into the bread and makes it Icky!

(Interestingly though, I do refrigerate the opened jar of jelly...whether it's homemade or commercially made)

No. I packed a pb&j sandwich for work today specifically because our fridge was broken and being replaced today.

I thought the whole reason pb&j became such a popular packed-lunch staple was because it doesn't require refrigeration!

No way. The whole point of PB&J is that it does not need to be refrigerated.

I do store my peanut butter in the fridge but that's because it's "natural" and refrigeration helps keep it from separating. I also store my jams in the fridge because eventually they will mold and they last longer in the fridge. But they mold in weeks or months, not hours.

I pack PB&J for long flights, too, because I know it will be fine for several days in a travel emergency. 

I don't ever take a PBJ sandwich, but this is what DS takes every day in his lunch. The reason he takes it is because (IMO) there is no need for it to be refrigerated. I don't think it matters about the jam.

In retrospect, I took tuna for lunch and bologna and ham etc... with mayo lots of times when I was in school and it sat in a warm locker for 5 or so hours before it was eaten.

You don't need to worry about pb&J.

When we were kids, we went to summer camp at the YMCA. They kept our lunch boxes in a small, enclosed shed until lunch time. A small concrete shed with a metal roof with no a/c, most of us had metal lunch boxes, in the middle of the summer, ice packs were not a thing at all, in Florida. It was probably 500 degrees in there.

I do not know how it is that we didn't all get sick. 

I have put a pbj in the fridge because I'll pack fruit and yogurt or string cheese or whatever else cold I'm having in my lunchbox and I just grab and go in the am. So if my pbj was on the counter instead of in my lunch bag in the fridge, I'd probably forget the sandwich.

So it's convenient for me, not cuz I think it needs to go in the fridge.

I do, but I don't know why. I think maybe because the jam is in the fridge to start with.

My daughter takes a PBJ to school for lunch every. single. day. We make whole loaves of bread into sandwiches at one time and put them in the freezer. She throws one into her lunchbox every morning and it's thawed by lunchtime - even in the refrigerator (their lunches get refrigerated at her school). No making an individual sandwich every day!

I don't, but I also make it in the morning, not the night before. 
Don't have problems with my bread. 

You can try making the sandwich on frozen bread. It will be defrosted and taste great by the time you get to eat it. Another benefit is no tearing holes in the bread...

I might put it in the fridge overnight then leave it out at room temp during the day before I eat it for lunch.  Jam, if left too long, can soak into the bread... but cold peanut butter is definitely icky!

While it's certainly safe to do so, in our house, with that scenario, it *needs* to go in the fridge overnight or you won't have a sandwich to eat the next day! One of our dogs likes to wait until he thinks no one is watching. Then he trolls the kitchen counters for whatever he can reach and pull down, and have himself a little feast. I even have to make sure there are no food remains of any kind in DD's backpack after school or he would chew right through the canvas to get at whatever might be lurking in there. We can't leave ANYTHING out whether it's safe to do so or not.