My Dad ped away, I am 17...?

My dad ped away on august 25th, 2008 very very suddenly. First off, I am 17 years old, and august 25th was my first day of my senior year of high school. My dad worked out 4 times a week, had been kickboxing for 10 years, ate right, and was just a nice human being. He owned a restarunt (which my mom took over) and always helped out his employees. On the 25th, he was at work in his office like any other day. When one of the employees buzzed down to the office to ask him something, he didnt awnser. So, she went down to see if everything was ok. When she went in, He was laying flat on the floor not breathing. They called 911 and they were there in under 5 min. The employee gave him CPR, and the hospital had over 15 doctors working on him, but he didnt make it. My dad was 56. Is it normal for me to start feeling sad and cry after a month?