well, i took it to the shop. they claimed they fixed it by "adjusting" the cassette ... looks like they put a different shim in between the 3rd and 4th cogs. very skeptical about this, and while it was quiet for a minute or two, the ticking came back. slightly different, but in all the same situations.
i do think after the feedback here and listening even more closely that it isn't actually coming from the BB area. it just sounds like it is, in part because that's where i'm looking to track when it happens relative to pedaling. the fact that whatever they did to the cassette momentarily changed it is suggestive of something.
there was a post a while back about the 5th cog in 12 speed DA cassettes clicking, will have to go back and see what the resolution of that was. my first one never did it, that's for sure.