Is this a red flag?

Been dating a guy for 2 months. We aren't exclusive yet, but a friend says she saw him holding hands with his ex a week ago and we haven't hung out in like 2 weeks. But he wants to hang out tomorrow. He says that he and his ex have broken up, but they're trying to maintain a friendship. I don't feel right about this, I think I'm gonna just leave. What are your thoughts?