My seller has a survey, so I don’t need a new one, right?

No. Surveys performed for previous owners do not protect new owners. The basics of contract laws typically exclude a third party from liability. So, the previous owner, or seller, may have recourse if he or she is the party that ordered the survey, but you, as the new owner, do not since you weren’t part of the transaction. Additionally, the statute of limitations for surveying errors is 6 years, so even the original client wouldn’t have recourse on older surveys.