If you haven't already, you need to give the title insurer (not the agency that wrote the policy) notice of this potential claim.  You are obligated to do so ASAP upon receiving any information that a claim could arise.  If you don't comply with the terms of the policy related to notifying the company promptly, the compay could have a defense to your claim.  The Owner's policy will contain instructions as to how and where the notice should be sent.

Now, having said that, unless your Owner's policy covers matter of survey (meaning the company was furnished with a current survey at the time of closing and issuance of the policy), you may not be covered if the issue is solely related to a survey problem.  In some cases, the company may issue survey coverage based on an older survey, if additional documentation was furnished.

Of course, just because the neighbor says the line is "off" doesn't mean the neighbor is correct, which is all the more reason for the title insurer to be notified promptly so that it can investigate.