Office politics or not, you have a problem when people start referring to parts of prod systems as "my code" or "your code". For me, from the point you opened a PR it's the team's code, not your own anymore. Everybody should be able to happily edit this part of the code without even thinking about asking for your permission (though asking for your input would probably a good idea), first to avoid this kind of nonsense and second because it avoids having people that are single points of failure (only one to work on this part of the code).

I would consider toxic a work environment where somebody would talk about "my code" after it's been merged.