How can I pursue this girl after she told me that she's only seeing someone?

To get more details check the previous question I posted on here. It's the same girl from work. I asked her last night if she'd like to go on a date with me and then she smiled and paused and said "well I'm seeing someone". Now I didn't get the worst vibe from this at all. She's a very sweet girl and as I said in my previous question that most of the guys in our job was going after her. However the ones that did and she had probably said the same thing to them, have kind of veered away from her. So I was just wondering how can I use this in my situation to maybe still get this girl? Thanks and I appreciate any positive advice.