I am not sure that I understand the question. The space between the edge of the widest label and the field looks wider when the color of the border is transparent because of the space around the colon. Other letters seem to have one pixel of space around them, the colon seems to have 2px. I’m guessing that this is what you might be asking about.
I do not know what you are asking… leave WHAT like WHAT?
If you are asking if it is OK to have padding on the left side of the lablel and not on the right side, the answer is YES. The words are still centered beneath the widest word in the available space as you wished. The padding is not “available space”; therefore, it does not affect the centering of the words, only their position in the invisible column. The padding adds space to the left of the words so they do not touch the fields.