Not saying you didn't, but I would have said the same thing after my ride to SLC during daytime when I didn't look. At high speeds, I normally don't look to see whether this tiny light is on. In the evening, I only saw it because it was getting dark. And, as I said, it would not be on at speeds below 70, so if I hadn't gone that fast, I would have never known.
Never had my cel come on at all despite over 500 miles since I did the mod.
So, have you deliberately checked your CEL at high speeds? That would then be a clear confirmation. Thanks.