Yes, I added a bit of salt when this began. Raised my level from 3200 to 3400ppm. I know the IC40's salinity calculation reads about 4-500ppm low. I finally got a response from Pentair yesterday AM. They're asking for receipts, etc.. They may replace it under warranty. Fingers crossed!
BTW, I have to do a partial drain next week to lower my CH (currently 775 ppm) and get the waterline tile descaled. After that, I'll rebalance the water and get the salt up to 3600 ppm. We'll see how that works! Thanks for all the advice.
The end to the story: After an initial slow response, Pentair stepped up and did the right thing. They finally got back to me (via email) and dispatched a warranty service tech. He showed up this morning. He quickly determined that the IC40 circuitry had "died" and he immediately replaced the entire unit. I now have a shiny new IC40 and it shows my salt level at 3800ppm!