I got a C on my first orgo and a A on the second one. And the same professor taught both classes. I got used to her exam styles and studied my butt off during my second orgo.
I was worried just like you up until the DAT day. When I scored 29 on the organic section, I knew I didn't have to worry anymore. Not one person during my interview asked me to explain the C, the one and only C I got on my transcript.
My point is that if you do well on the orgo section of the DAT, you should be fine. Do not worry about it. Do spend your worry time studying!