yea one of my recommenders did the same thing, and i had him change it to "dear law school admissions" before he sent it in.
i think it's worth making the change since it may give the school who is reading it the impression that the letter was not meant expressly for them, but of course, admissions know that if you use LSAC your letter gets sent to every school.
so i'd say if it's not too much of a hassle, go ahead and get it changed, but it probably won't hurt you too much.