Just catchin' up. Like you, I'd be wary of the friendliness. My WAW and I hadn't made love in quite some time (this was before I discovered the A and she filed). Then, on our anniversary, she was all over me. At the time, I thought maybe the great thaw was on. Turns out she'd had the OM in our home just 48 hours before and had talked with him for a half-hour just before we had dinner that day! She was feeling guilty as hell and making love was her way of salving her conscience.
There's nothing wrong with her being friendly, but before you hang your hat on it, so to speak, I'd want to see a real trend...not just a single event.
You know, it isn't talked about much on these boards, but I think that for some WAS...especially those that feel they did not have the influence or control they desired or deserved in the M...may use the being nice thing as a way to exert emotional control over the LBS. To string them along or even the score, in a manner of speaking. I'm not saying that always happens or that it is in play in your situation. But I do wonder if it occurs in some cases.