Hopefully this screenshot will help me show you:
See how there’s a thin line above the cat’s ears where the chair shows through? And see how the cat is offset by half a “pixel” horizontally from the chair?
If the game was 64x64 pixels then there’d be exactly 64x64 squares and each one would have just one colour. Like, if you create a 64x64 canvas in Aseprite, you can’t draw a cat that’s 20.5 pixels wide. It’s gotta be 20 or 21. The fact that the cat is offset from the background image by a fraction of a “pixel” means there’s far more than 64x64.
I honestly wouldn’t sweat it. Quite a lot of devs have submitted higher resolution games, and quite a lot of voters don’t care. I care, and I point it out because it’s an important factor to me in a low-res jam – but I stink and I’m a dork, and no-one should care what I think. :)
And look, even with all that said: you got easy 5 stars from me for audio and graphics. It’s a beautiful game, you should be proud of it, and I hope it does well in the ranking!