Well, I was worried about my bail bondsman status (and possible penalty) for nothing, so far. The certified letter turned out to be unrelated to that. In fact, I heard from the person in question last night and was somewhat already assured that there was nothing in the works, known at least.
But still, I was up and it occurred to me about 8 a.m. again about the certified letter. So I hustled over to the post office, then had to stand in line behind someone with several eBay packages to process (just my luck), and finally got the letter. I saw the return address and realized immediately that it was business that was quite benign and unrelated to any personal issue. Someone had sent some checks and I'm the middleman to get them where they need to go. That's all.
But this had never happened before, and it's timing was curious, making it a realistic first guess that they could have been trying to notify me about the bond.