Correct. The outbreak was first recognized in 1975 in Old Lyme, Connecticut, directly across the Long Island Sound from the Plum Island Animal Disease Center (a lab which had been doing explicitly offensive biological weapons research until at least 1969), which led to an unverified theory about an escaped bioweapon.

Genetic studies and museum tick specimens prove the bacteria existed in North America for thousands of years before the lab was built. Whether there was gain of function done on it is not publicly verified.