Thanks Lars. The full quote from the development blog was:
So I was curious whether that actually made it to production. I ran a quick test (coded a module to intentionally output NaN and inf). Indeed, the module output (cable input) showed NaN or inf. But at the cable destination it shows as 0. So the blocking by the cable truly is occurring.
Unfortunately for me, that means my S&H module must have been producing the invalid output on its own 
So I have a bug to track down, but now I can’t seem to reproduce the problem. Argh.
I guess I am past due for an inscrutable bug in my Venom plugin. As a fairly new plugin developer, I’m a bit surprised I haven’t run into something like this before.
So please - if anyone runs across invalid output from any of my modules, please let me know. Especially if you can reliably reproduce the problem, please post a message with a patch and instructions on how to force the problem. That would be a huge help!