I looked back here and remembered reading something...
You opened the hood of a truck that was not yours? The owner was not around? That just isn't right, man. You don't have the right to touch another persons property without permission. I'm sure you wouldn't want a stranger to walk up to your car and open the door sit in the seat, play with the steering wheel or shifter.
In the 80s we had a neighbor that would come over to our house and do this. My Dad sold GM cars and was allowed to drive cars home from the lot. This idiot neighbor felt entitled to his behavior because the car wore the plastic dealer plates. My Dad came out one day to see the guy (Who drove a Volvo) with the hood open and sitting in the driver seat. Dad told the guy to GTFO of the car and said it with meaning. The clueless idiot acted as if he had done nothing wrong at all. Keep in mind this was the type of guy that would pick his nose while talking to people face to face.
People have complained about kids or adults messing with their cars at car shows. Others have mentioned guys like Galen Govier opening hoods or moving dash covers to get a look at VINs or fender tags. This is equally offensive.
I have stood close, looked underneath and peered inside but never touched a car unless it looked abandoned.
I can understand being anxious about the truck. We have all been in that position. You have to respect other peoples property though.
Good luck with it.