To me it sounds like something on the live site is looking at the staging site.
First things to look at, are is there any queries or such that are accidentally referencing the staging site through a full table name (ex: [Kentico_staging].[dbo].[CMS_Tree])
Second, i would look to any custom global module loader that may be catching certain page events and automatically pushing them.
Thirdly, check your hosts, make sure you're looking at the production server.
Fourthly, take a look at the database, find the record and see when it was last modified, was it pretty much instantly after you made the change on staging, or what was the delay? are there any other events that occurred around the time of the modification?
Some good places to start.