My first mopar "stranded" moment with the HEI setup

Well it happened yesterday, driving home in my 66 dart 270 sedan full of groceries. Stopped at a light, then the car just stopped dead. Tried to start it and just spun with no spark ( I guessed). I have had the car for almost 2 years and had recently (2 months ago) completed the HEI swap from the old points. I thought I was feeling over confident that the car was stable and good to go for years to come.
(I am new to all of this mopar stuff, learning from you guys on the site and reading materials)

So I got out and pushed to get the car to the side of the road. Waived people to go around me (no e flashers on this car). Popped trunk, got out my bag of tools. Popped hood, everything looked ok. Why in the hell wont the car start? Gotta be ignition issue? So the only thing I could try was the ignition module. And yes, thanks to you guys on this site, I had a spare module in the glove box. Because of how I installed the GM bracketry it is a serious pain to get that module off, but I did. now grey paste all over my fingers. Put the new module on, reconnected battery. started right up. Whole thing took me about 15 minutes.

Now if you have read this far my question is: Why would the module fail? It was a Standar Motor Prod LX301 for $35 on Amazon. (which I have now asked for refund).
I had noticed the last few mornings when I started the car it was sorta rough for a few seconds, but then evened out. Was that a sign that the module was farting out?
Time to order another spare. When it started up, the first thing going through my head was, I do not have the stomach for the HEI, and the points are going back in. But I have since thought I would give it another try and see if it happens again. Fool me once, shame on you. Fool me twice HEI and shame on me.:)