Slow hot start after sitting

I have noticed that it takes a few extra seconds to start after the truck after it has been driven, engine is hot and it sits for about two to three hours. I have not noticed any problems on quick start and stops when hot. Normally after it has sat for a couple hours. Not easy to reproduce, but seeing a pattern.

Sometimes I turn over for a few seconds, wait a few seconds, then on a second try it starts fine.

-First noticed this about two years ago, but only happens now and then.
-Always starts after sitting all night or all day.
-Only notice if engine is hot, and has been sitting for a couple hours.
-Truck always starts, has not left me. Just notice a slower/longer start.
-Truck runs fine once started.

I was thinking fuel pump since it is original, but thinking it is temperature related have not replaced.
(But may put it on the list just because its easier to do this over a weekend, then on the side of the road)

Considered voltage issue, but battery seems strong, good voltage on startups.
(I have not checked voltage at relay or pump, so intermittent that not sure it would show up)

My first guess, because I have had a similar issue on Honda's, is a sticking fuel pump relay? It is located under the hood, near the firewall? I guess the higher temperatures and sitting could cause it to stick. Like I mentioned, I had a Honda Civic and Odyssey both have fuel pump relays stick and cause similar situations.

At this point I have not changed any parts.
Did not want to start throwing money at it until I had a better idea of whats going on. But with my son driving it now, I would like to fix it.
I have explained this situation to him and he has reported that it is taken a little longer to start a few times, in the same situation. Last night he went to a friends house for about two to three hours, and noted that it turned over a few extra seconds before starting, then fine. But even after sitting in a hot parking lot all day at school, it seems to start fine. So not outside temperatures, but hot engine temperatures?

Thanks for any advice.