Right now, the leadership has to keep the potential Democratic filibusterers isolated. Being the 41st vote to stop Obama/Reid/Pelosicare would be a very uncomfortable position for any Democrat. Being isolated makes each potential filibusterer more vulnerable to party wrath. On the other hand, being part of a group (albeit a small group) of filibusterers could offer considerable protection. Leadership might be able to turn against one of you; it would have a harder time turning against four or five.
So we see this weird dance going on, in which would-be filibusterers can hide in a fog of other potential filibusterers. It's in the moderates' best partisan interest to look out for each other and offer potential objections and suggest that they may filibuster. Meanwhile, the leadership is trying to pick off each of these moderates and make all of the moderates feel insecure about the intentions of the others to filibuster. Leadership may be succeeding in this attempt. If the moderates are serious about bringing a real reform to this bill, keeping a united front (and being certain of the willingness of the other senators to filibuster) could be a key tool in forcing real changes in the bill.