First I will start with a rhetorical question -
If you were puzzled, why didn’t you ask on disembarkation? Most pilots are a friendly bunch, and are quite happy to have a quick visit to the Flight Deck.
Onto your questions - (and any answers you get here will be pure speculation)
1 - possibly streaming, then decided against it. I have had numerous occasions where ATC have asked me to either speed up or slow down, then shortly after they have changed their minds and we have gone back to “normal” speed.
2 - was the Flight oceanic by this stage? If so, are there US offset procedures that includes flying at an out of the ordinary level? I’m clutching at straws........