The symptoms normally disappear after several days and there are no adverse health effects.
The cause of pine mouth has not been determined, but several researchers have indicated that a particular species and source of pine nut, Pinus armandii exported from the Shaanxi and Shanxi regions of China, may be responsible for causing the symptoms. This species of pine nut was previously only consumed locally and not widely exported for consumption as whole nuts.
Pesto contains pine nuts.
Not sure if that helps or answers anything tho.
Edit: From a different comment here, they mentioned pine nuts being the cause for them. Seems very plausible then.