Well, I did voice outright that I was uneasy with it, but in such a way that implied that it'd be fine after I got used to the feelings, which I thought was true at the time. After more thought, I realized it wasn't really something I wanted
to be comfortable with in regards to this particular person.
If I could have gone back and changed things, I would have asked her to hold off on it until I had more time to figure out my feelings, but doing that went very poorly in a past relationship, so I told her to just go for it and not worry about my current feelings on the matter. If nothing else, the experience has taught me that I shouldn't and needn't be afraid to ask such things of her.