Distributors will notify you of recalls, but no distributor of electronics i've worked with notifies you of erratum (and it would be really annoying if they did, honestly :P)
This reads like it should have been a recall. But that's hard to tell unless I knew exactly the specifics of the issue.
Did NASA assume these were rated higher then they were? Did Infineon make a mistake in documentation, or did they straight up not test them or test them incorrectly.
Unless contractually specified otherwise, it's generally up to the buyer to check the delivered goods for defects and report those without undue delay*. If this is not done, the goods are deemed to have been accepted.
Sure you can contractually specify that the product has to meet certain specs and pay extra for the seller performing QA, but the default often is "you're buying whatever comes out of our factory, check the goods yourself on delivery". The reason things are done this way in the business world is that it is generally cheaper to accept certain failure rates than to perform testing at every step of the supply chain and add a whole lot of bureaucracy and complications because of returns.
Whether custom contracts existed in this case is unknown, but it is likely that Infineon notifying customers was already a courtesy. They could've just said nothing.
* Under German law, which likely applies here since that's where Infineon sells from.
IANAL, but I would think Infineon's data sheet and quote would constitute the "offer," and NASA's purchase order the "acceptance." IIANM, this meets the minimum requirement to establish a "contract" (usually called an "agreement" these days).
If the MOSFETs don't meet the specs on Infineon's data sheet, including rad hardness, then Infineon would be in breach of contract.
If NASA accepts the delivery of those things and doesn't check for & report defects*, then outside of willful deception on the Infineon's part, it's not the Infineon's problem anymore. It is the responsibility of the buyer to check that the items are as specified. If the buyer neglects that responsibility and signs for the delivery, the seller is off the hook.
German law differentiates between "open deficiencies" and "hidden deficiencies". If you neglected to properly check for an open one, that's on you. You now have no warranty under the law. In case of a hidden one, which will likely only show during large-scale production and can't really be detected beforehand, you have to immediately report it once you discover it, and it is your responsibility to document & prove that you did so without delay.
Under this system it's up to the buyer to decide how much reliability they need. They can forego testing and save money because it's not important to test every single screw when building a garden shed, or they can rigorously test every single thing because they're building a spacecraft.
* It is enough to prove that you did perform checks. If you got unlucky and the random samples just happened to be good, you are still protected. But if you didn't check at all or not sufficiently, you're screwed.
