Property line question

[Keith Shackleford]

Less than a year ago, I purchased a home from a rehabber (one of the ones that have a TV show).  The home came with a one year warranty. Yesterday, the owner of the tri plex was here with a surveyor and informed me that the front fence and part of the HVAC units were on his property (about 18 inches).   Since this was added by the rehabber and no survey was done, is it his responsibility to fix the issue or mine?