I myself have used independent distributors to cover small-quantity shortages as the original poster mentioned. Other OEMs do the same - their buyers do this "under the table" so to speak (off the approved vendor list). If the material is in original boxes then you can safely say it's ok. All bets are off if the seal has been broken. I had one batch with dead parts once. Failure analysis showed wrong die inside - the outside marking was bogus.
By contractual agreement franchised distributors can refer their customers to manufacturers for technical support (because the questions tend to be application-specific and distributors are just basically warehouses), and manufacturers are pretty supportive about it in my experience. Independent distributors are not recognized by manufacturers. As a matter of fact independent distributors are often considered the cowboys of the industry, peddling parts of unknown origin. Having said that, there is a place for them in the food chain. You just have to be really careful.