They may not have even written it down. Unless they had to apply for a warrant to search the place where you were hiding, there is no need for them to ever reveal that information - more so if there is some reason to believe that you might retaliate.
When I have someone tell me about the location of a wanted suspect I write it off as an "anonymous tip" if I have to write it at all. Unless I have to take some legal action such as obtaining a search warrant, there's no real need to mention it anyway.
So, chances are there will be nothing you can do short of getting the officer who answered the phone drunk and getting him to blab.
- Carl

