what does it mean when girl says?

This girl and I have liked each other for months but she has just come out of a relationship, we've kissed every time we've been together for the past few weeks (no tongue) but I was with her at a friends party yesterday and when we were kissing everyone burst in and made it really awkward, it was a goodbye hug/ kiss anyway because she was going home & she left pretty hastily while smiling at me. But today she said she was sorry that she kissed me, not in the way like "I'm sorry I kissed you because I'm not interested or you're a bad kisser" like she was actually apologetic for kissing me even though we're both single & like each other... What does she mean? We're taking things really slow anyway but just any advice is appreciated.. Thank you :)