Proper procedure indicates that yes -- it usually should be. Corrections in insignificant things such as spelling are of course less critical, but anything emergent to timely needs to show when the noted changed was detected. Likewise, I suggest that the change is initialed.
Note also that corrections never ever eradicate what was erroneously there before. The old entry is single-line struck out and the correction added. The exception to this is corrections asked for by the patient and made by the doctor, under the HIPAA guidelines.