to your question - Has Christine graduated to piecing? Well, I think that posting in piecing is a self fulfilling prophecy - if you say you are then you are.
As to his behavior - it sounds just like my WAW - it seems that they have made up their minds that the M is over then they catch themselves really having a good time with you and then start thinking "what am I doing, This R is suppose to be over. But this is fun, What's up." then they withdraw back into their cave to start sorting through their feelings. this is the time to give them the space they need to sort through their feelings without any pursuing or pressure. The last thoughts of you are very plesant ones and the space will create an emotional vaccuum that will draw them back. As they are drawn back then DB your heart out again.
The cycle continues but each time (at least for me) the next cycle is usually better and better and the down times between great contacts are less and less. I now can expect the down times and knowing that it is normal, use the space myself to work on ME, content that all is going well.
Keep DBing and Keep piecing. (keep swimming, swimming, swimming...) and have a great day