The Great Cookie Swap Fiasco

So here's a funny story about my sister and me. Yesterday, we were both craving cookies after dinner, but our parents had hidden them out of sight to keep us from eating too much sugar. I got an idea, why not switch places and pretend to be each other? My younger sister is super small, so it worked like a charm! I sneaked into her room in the middle of the night and left a note saying 'I'll get those cookies for you' before running back to my bed. But now she's mad because she got caught by mom instead, and I'm not sure if I should apologize or just laugh this off. What do you think? Is it normal to feel guilty and amused at the same time?