Text logo vertical alignment

I have a 40 font type text logo on a 400x400 image size, being mathematically centred both horizontally and vertically, giving equal pixel distances at all 4 sides of the said text logo.

When creating an increased image size and font type size to 50 font type and 500x500 image size, being mathematically centred, I am achieving equal pixel distances left and right of the said text logo but not above and below. There is 1 pixel difference with the vertical centre alignment, due to the nature of the font type increasing in size unequally. The Photoshop program chooses 159px at the top and 158px for the bottom. Is this correct protocol for mathematical vertical alignment?