The concern was that he had dropped from the 25th percentile to below the 5th between his 4 month and 6 month well baby checkups. So the doctor showed me the chart today and explained that he wanted to make sure that Button's trajectory was consistent rather than continuing to go down, and it's now consistently the 5th percentile, so basically my little guy has set himself a new growth pattern.
I have to say, I don't love this particular doctor. He has a tendency to ask a question and then keep talking so that I can't answer, or he'll only listen to part of something I say and I can see that he's reacting before I've finished talking so that he's not actually listening to me anymore.
I do like the other two doctors and the physician's assistant though, so I think I will stick it out with these guys unless they do something to make me angry.
Anyway, they are finally convinced that he is growing just fine and that part of the reason he's thin is that he's so active (they seem to be completely ignoring the genetic factor). Maybe it's good that Button has been on a bit of a feeding frenzy lately...he probably gained most of that weight in the past 3 or 4 days!