I would write a concise letter to DL, outlining what exactly happened.

I would point out that the police did not detain you and that this is a strong indication that they, too, felt that the FA's response was overblown.

I would say that I expect that this incident will be fully investigated, and that I feel a formal apology from DL is warranted (mention the unnecessary embarrassment of having been escorted off the plane my law enforcement).

I would conclude by pointing out that I do not expect any repercussions with regard to how I am treated by DL in the future and that I would appropriately respond if I have reason to believe that I have received any inappropriate treatment.

[Oh, by the way, prepare to be flamed by folks who will assert that you are making this all up.]