30 days after going down? Doesn’t seem likely; but who knows.
This type of sample and the lab procedures have been in use for several decades to ID the source of open ocean hydrocarbon sheens. The purpose is usually to track down the tanker or product hauler ship or perhaps a drilling or production platform or undersea pipeline with a foul up that spilled hydrocarbon so that they can be fined and if there is deficient equipment involved, force repairs.
BTW... The so called expert quoted in the news article is an idiot. I hope he gets flamed in his next job review. If they had wanted expert information, the news reporter should have contacted the Coast Guard to input directly or recommend a legitimate private expert. Or heck, just get the Houston, TX yellow pages and call up some commercial labs specialized in oil industry applications and talk to the lab manager.