dating someone who had a fling with my best friend

Even though my best friend and he hooked up once, they never officially dated; they only talked and occasionally spent time together. We were discussing him and noticed that we share some similarities. She gave me her blessing to talk to him, and we've been chatting for a little while now. I'm beginning to develop feelings for him, and if things progress, the intention would be to date. It doesn't really bother me that they had that experience, but I do wonder if it might affect me in the future. They still have some contact since we all attend the same university, which means we run into each other sometimes. Am I overthinking this, or do I have valid reasons to reconsider pursuing him?