It is possible for error, but if you really want to put your mind at ease, you can instal MyLookout, or Androidlost on his phone, and that will be much more precise, and give you exact location of the phone. Or you can simply ask him and either believe him or not. If you have doubt right now, that is not good IMO. Good Luck, keep us posted as I will be curious to find out the end result.
Androidlost can be installed remotely if you have access to his Gmail account.