My WAW and I do things for each other all the time. There is no reason not to be friends. The contact may give you the opportunity to grow your friendship. Just don't pursue.
This had been working for me, up until she told me that she wanted to start dating me. With hindsight, I now understand that she wanted to spend more time with me, her friend; she wasn't ready for the next step. It was my error. When I started discussing our relationship and setting boundaries, it scared her off. So, be careful.
