No you didn't, you failed to notice a slight drop (over 3 degrees at cruising height). Others are more observant. I can be sure of this because the shape of the Earth does not change just when you fly.
Does True Randomness Actually Exist?

Next time you fly be more observant of the earth -
I flew all the time(30 to 40 years) and never really paid much attention.
I remember flying into Anchorage Alaska back in the 80's and never saw so many Jumbo Jets in my life all stacked up with people(staying on the plane) from all over the world in such a small airport compared to many like LAX or Chicago but nonetheless 747's, DC-10's where everywhere!
When I asked someone the reason for this they simply said the airport was a major refueling hub for international flights.
Never really thought about that either until about 10 years ago.
Then it made perfect sense

So, they told you the right answer.
You do understand that that is a part of the world with very few people and thus widely separated major airports? Anchorage has very little competition, so captures the market for a large number of long haul flight stops.
For example, the nearest airport in the top 50 is a very long way away, in Seattle.

Yes, had to fly through Seattle prior to Anchorage then on the Juno then to my destination Yakutat Alaska -
I think the Fairbanks airport in Alaska became the main new refueling hub for international flights.

Yakutat was an adventure to say the very least - ended up stranded for a few weeks before I could hitch a ride on a plane out of there - long story !
I went to work for a friends father who was running a lodge for mostly "jet setters" & hunters/fishers.
I don't recall any famous surfers nor any surfers at all. Did see a glacier. Lots of bears - grizzlies - I think Kodiak Island is not far from Yakutat.
I see the population hasn't changed much - it was 600 plus when I was there back in 1986.
Ghost - I had an aisle seat & observed the horizon "eye level" from either side of the fuselage/cabin windows - while seated.