Maybe the CFI thought you forced him off the runway surface.
91.113
(g)Landing.
Aircraft, while on final approach to land or while landing, have the right-of-way over other
aircraft in flight or operating on the surface, except that they shall not take advantage of this rule to force an
aircraft off the runway surface which has already landed and is attempting to make way for an
aircraft on final approach. When two or more
aircraft are approaching an
airport for the purpose of landing, the
aircraft at the lower altitude has the right-of-way, but it shall not take advantage of this rule to cut in front of another which is on final approach to land or to overtake that
aircraft.