Hmmmm, I hadn't noticed that before. Now you got me thinking. You've noticed too no doubt that when you click on 50ft for depth you get the response "new depth....49ft" or you click on 100ft and you get the response "new depth....99ft". Just a little off center so to speak.
Coincidence or giant conspiracy to mess with our minds, LOL???
In short, I think both issues are simple interface bugs. Not sure if they're moddable.