Thanks, a lot for your help.

This allowed me to find the actual issue whilst trying to make the changes.

Answer: There was no misalignment, only a visual appearance of one.

The labels were centered, but looks to be aligned on the next tick's over quite well, thus giving the impression it was offset.

Fixing the xticks alignment ha to 'right' fixed the issue.

plt.xticks(rotation=45, ha='right')