Watch out what you put into your bathroom cabinet

I live in a small flat with my sister. Last month I did something really stupid. It was actually an accident and I really didn"t mean it, but it caused me a lot of trouble. It was the day of my final exams at school so I got up early, quite nervous. I didn"t feel like eating anything so I just had a cup of strong coffee. It made me even more nervous, but I had to get dressed, pack my bag and leave home soon. When I was about to leave, I noticed that my wallet was missing. I started panicking a little because inside there were many things that I needed: my credit card, some cash, my ID and my train ticket. I asked my sister for help and she finally told me to check in the bathroom cabinet. Well, my wallet was really there! I thanked her and said goodbye to her because she was leaving for New York that day and I wouldn"t see her later. Then I went out and she closed the door behind me. My exams were not as difficult as I had thought. I actually needn"t have worried because I passed with flying colours! After the exams I went to the pub with some friends. In the evening, at about 8 or 9 p.m., I was finally sitting on the train, going home. I looked inside my bag to make sure my wallet was there. I could have left it in the pub, it was a crazy day. The wallet was there, but the keys to my house weren"t. My sister had locked the door behind me that day. Had I left my keys in the bathroom cabinet?