sounds like she wants to just have fun. the ones that dont seem like the type of girl are usually the best fun. Take the advice from the other lads and be cool, just tell her that you werent looking for anything seriuosly anyway and glad she has brought the subject up cos you were worried she was going to get heavy, be brave tell her this and I bet you it works. fun can turn into something else down the line if you really like her but if thats all she wants at least you get the fun bit.