How to deal with the thought of something I did when I was a child?

When I was a child, a friend and I were exploring some woodland when we came across what I remember as a dead cat. Wanting to hide it from the world, I placed a concrete slab that was next to it (not sure why it was) over it and thought nothing more of it - until a few days later when i was back there and I removed the slab to discover its flattened remains. This image has haunted me recently - making me think 'what if the cat wasn't actually dead when I put the slab over it?' I'm pretty sure it was - my friend and I had both agreed on it and there must have been some sort of evidence like maggots or something, but still, the thought of it haunts me. How would I deal with this?