I've noticed this happening a lot more, too. It's kind of a pain, but I don't think it's a problem. I think it means that drivers are realizing that there are bikes on the road, and that the bikes have a right to be there and need to be accomodated.
The problem is just that they don't quite know how to do this. But I'll gladly accept this problem over the problem of drivers not knowing that bikes are on the road, or not accepting that bikes have a right to be there. Over-politeness is, frankly, a problem I'm happy to deal with.