Look at it from their side. The first they hear about the problem is a blown blower on the customer's car. The first one may be a fluke, so they do the warranty repair. They get another, and the red flags go up. Bad parts batch.

Now, how many are bad? All of them? Not likely. So you have a recall/repair the bad ones decision. A recall costs you more and may hurt your rep worse than just fixing the bad ones and eating some ancillary costs.

Sounds like they are acting fine, so far...