Why would a rabbit be bothered ?

I have got two rabbits who I bought from a rescue shelter a couple of years ago. They live in the garden in a hutch with a pen attached. Whenever I clean them out I let them run loose in the garden for a while. The other day one of them sneaked into next doors garden when my back was turned and went right up to their house. I shouted 'Topsy, come back!' and she turned round and looked at me and came right back into my garden again. The next day she did the same thing and the man next door was in the garden. I shouted for her to come back and she turned right round and came back again. The man looked at me ever so strangely. Does this mean she understands the words or just the urgency in my voice? I wouldnt have expected a rabbit to care really.