Is it normal that i get hard when i try not to

Every year I drive to southern France with my girlfriend in a rented camper van. We are both nudists and we always stay at the same nudist camp site.
It's quite a large camp on the sea front. To one side is a normal site and in between there are signs to let people know that they are entering a nudist area.
One day we were laying on the beach until early evening Maggie went on ahead start cooking a meal. I fell asleep for a bit and woke to see that the sun going down and the beach was almost deserted.
I was laying there at the bottom of a dune and put on my tshirt. Maggie had taken the towels and everything with her.
I looked around to see a group of 5 young girls arounf 11 or 12 walking nearby, Then they came straight over to me and asked me the time.
First I asumed that they were staying at the same campsite as me as there are many families with kids so I didn't treat anything as being out of the ordinary but then one of them was playing with a torch and she kept shining it on my dick.
They also kept on making conversation asking me stuff like where i was from and how i found the area.
I kept getting all kinds of questions from them, the torchwas continuously shining on my dich and there was a lot of giggling and whispering going on between some of them
My attitude was to act normal. I didn't want to try covering myself up because I didnt have a towel or anything and the idea of covering it with my hands felt a bit odd and unnatural
The biggest problem I had was that I realised I was beginning to get a stiffy.
There were absolutey no sexual thoughts going through my mind but once aware of it I seemed to have no control over it. It was growing hard and my willing it to go small again had little effect.
I wanted to get up and say I had to go but that would mean walking past some people while erect so I sat it out pretending that I hadnt noticed it but they obviously had
It's funny how kids can whisper and expect no one else can hear. They were still giggling and I could hear references about my dick.
I then had an idea. I said I was going to bury my legs in the sand so they wont be cold and in the process covered my genitalia.
Well it seemed that my idea worked and the novelty had wiorn off because theysuddenly remembered they had to be somewhere.
What I found a bit disturbing was how easily I could have been seen as a pedophile when I'm 100% certain that I am not. I wouldn't go out of my way to expose myself to minors.
I was in the right place to be nude and they came to me. I didn't go to them.
As a believer that nudity is a natural state and no one should be embarassed about their body I tried to treat the situation in a natural way feeling that trying to cover up or hide it was like saying it was not natural and should be hidden.
My main dilemma was the fact that I had an erection from it even though I hadn't a single sexual thought in my head.I'm curious how others would see it