Listening to channel nine on UA 1225 Denver-Reno yesterday, I heard
something like:

"Denver Center, Jackpot 123, can we request a block allocation
for 39 to 41?"

and then

"Jackpot 123, Denver Center, block allocation 39 to 41 approved."

["Jackpot 123" is made-up name since I don't remember actual name; maybe
it was "block assignment" instead of "allocation"; and I don't recall if
the wording was "Flight levels 39 to 41" or just the numbers.]

Anyway, I'm assuming that "Jackpot 1243" wanted to move up and down
freely between 39,000 and 41,000 feet seeking smoothest ride and best
fuel economy without having to make repeated requests; and Denver Center
was willing to approve this since nobody else was up that high anyway.

Is that likely the case?