Ah, gotcha. Not using custom domain is really screwing things up, isn’t it?
The original implementation of ActivityPub in Micro.blog required custom domains, so there’s just a lot of little things we didn’t account for with how Mastodon works. I’m testing a fix now, though.
I’ve made this change. Let me know if anyone notices any similar problems.
I’ve noticed this on my timeline again, @manton. Here’s one entry with comments from the Micro.blog community and another with a comment from Mastodon.