"at least 2 separate buyers have to go after you "
That is the official policy. However, if one American buyer with multiple purchases decides to leave a 1 or 2 on any subject on all purchases, ALL will show in your dashboard.
eBay has a program they run monthly to filter such instances. However,
I know from personal experience it does not always work. eBay is aware of the problem and are working to correct it.