WJB, welcome to the fold! Over the years I've enjoyed this forum almost as much as the running. Things can get blunt, overheated, downright rude at times but, like fell running, it is the refreshing freedom to express yourself with like minded individuals that makes the forum so addictive (for a very tiny, sad minority of the fell fraternity!!). In your case, I think the football analogy is very pertinent. If someone joined a game you were playing and then whined that they did not know about handball I suspect you would think they were a bit of a twat and, at the very least, disrepectful for the spirit of the game. So can I suggest that you reflect for a moment about turning up to your first fell race without first checking what was involved? And how you might prepare yourself? Without wanting to sound preachy, and at the risk of repeating myself, it comes down to having proper respect....respect for your own safety, the responsibility of the organiser, the terrain you are committing yourself to and the spirit of wild racing in the hills.
But, no harm done, you've done the right thing and bought the appropriate kit. Just sling it in your kit bag and take it to EVERY race, no matter how short, flat or hot. Then you will always be one of the sensible majority who just get on and race in the proper spirit and not one of the spoilt complaining brats who make life hell for RO's by always trying to bend sensible rules that have absolutely NO effect on their performance.
Were you guilty of cheating? Of course not. Choose your own from ignorant/silly/presumptious/thoughtless/etc etc!