What are you talking about? I said the earliest canonical gospel, Mark, was written at least four decades after Jesus's death. The others were written later than that. And I said the lateness is far from the only problem with them. But I can tell you're far from being steeped in the critical history literature since you're talking about Bart Ehrman (not Herman), and you accept the traditional views of the gospels' authorship, which has been rejected by the consensus of critical historians.

On Luke, for instance, 'According to a Church tradition, first attested by Irenaeus (c. 130 – c. 202 AD), he was the Luke named as a companion of Paul in three of the Pauline letters, but "a critical consensus emphasizes the countless contradictions between the account in Acts and the authentic Pauline letters."...

'The eclipse of the traditional attribution to Luke the companion of Paul has meant that an early date for the gospel is now rarely put forward. Most scholars date the composition of the combined work to around 80–90 AD, although some others suggest 90–110, and there is textual evidence (the conflicts between Western and Alexandrian manuscript families) that Luke–Acts was still being substantially revised well into the 2nd century.'

https://en.wikipedia.org/wiki/Gospel_of_Luke#Luke%E2%80%93Acts:_unity,_authorship_and_date