Take her at her word, it doesn't mean anything. If you are okay with that, carry on. Like Starsky said, use protection. As much as you think there is not another person, most of us were just as sure.
Proceed with caution. There are different points of view on the subject. Some say it helps the two of you to hold on to the physical bond which, in turn, helps the emotional bond to grow. Others say it is just her asserting her control over you. I am no pro, but I tend to agree with the latter. Us guys are simple and sex, especially the wild monkey sex my W was newly interested in the few times we did it. It was great, if you can picture your W someone you pick up in a bar and take her home for the night and she lets you do things you had only dreamed of up until that point. In my case, the woman I woke up with was not the same one who I fell asleep with. She wasn't my W before or after.
I really miss the sex, but I miss it with my W and I don't think that's what we usually get in this sitch.