My teacher lowered my grade on a project just because......?

I procrastinated. I was supposed to create a legend or mythical creature. I didnt do it till home room and was able to write 1.3 pages. I got an A- because my handwriting was really messy but it was very imaginative. When she was handing it back to us and my friend saw my grade he whispered "I cant believe you did this in homeroom". Then my teacher grabbed my paper and gave me a B-. Do you think this is fair? I always either procrastinate but I am more likely to finish homework in cl and still have spare time left especially in english and math.