Texture Alignment Question

[hl3_exe]

Hi, I'm a bit confused with texture resizing and alignment.

Whenever I download a 2048x2048 texture from FPSBanana and compare it with a Valve texture that has been resized to 2048x2048, the images are always misaligned by 3 pixels.

I noticed, in the bottom-left corner of every Valve texture, there are 3 pixels each colored red, green, and blue. Obviously these will become 2x6 pixels when rescaled x2.

Now I'm thinking this is the reason for the misalignment. The question is, what are those 3 pixels and must they always be 3 pixels irrespective of any scaling?