Yeah, seems like a standard supply level to me.

"California’s inventory has averaged just over 20 days of supply over the last five years (2019–23), compared with the U.S. average of 21.6 days."

https://www.eia.gov/todayinenergy/detail.php?id=63944

I think they mean that it's 4-6 weeks until they hit zero, accounting both for stored products and the current rate of production/imports.

Usually when something like this is reported, it is because of some other milestone.

Like, they have 6 weeks, on hand, in tanks already delivered.

But, all of the ships in-bound are now done.

After the war started, there was a record number of ships, already filled, already in-transit. But now they have all reached their destinations. So there is no more incoming.