Thank you for talking me down, people. And making me laugh. Of course he is fine - he's better than that. Part of my trouble here is mental: he kept reaching milestones ahead of schedule in the early days, so I sort of have it in my head that he is a highly advanced child. Which he of course is. ;) But his tummy muscles don't know that.
Interestingly, after I wrote this post, he starting rolling over like gangbusters. He's done it half a dozen times since then. Like he is saying "See Mommy? No big deal."
He did that in the womb, too. Every time I would convince myself that he had stopped moving, he would start doing the Cha Cha Cha. I thanked him a lot during those days.
All of this is really great for me. But I am (only slightly) concerned about this constant reassurance that he is providing. What if it turns into the dysfunctional cycle of co-dependency that I share with my own mother? I do want him to be like me in other ways, but it would be great if he didn't require the mother-related therapy that I do. Or maybe I should just start a savings account right now. How many 6 month olds have a piggy bank in their rooms labeled "Future Therapy Bills"?