Well, that’s what it looked like to me. One guess what it is.
One of the reasons I really like working with hand planes is that you can really finesse work pieces to the nat’s eye lash. Understand that can be a bad thing too. But when doors, it really makes it easy to be able make a perfect fit by taking off small bits here and there.
One thing I learned when siding the house is that you don’t need to make things level, they just need to look level. When I put up siding, I made sure it was parallel to the window sills, which are not level in a 100+ year old house.
The same thing applies when making a cabinet .. it just needs to look square and even, it doesn’t always need to be exactly square. Of course making it perfectly square every time would make for less futzing around. But hey, I’m rarely perfect in my execution and my hand plane usually bail me out.