I think what Anderton is saying is that the note doesn't start exactly on the beat, but the snap-to is set for an exact beat, or measure, so the note-on event is before the place where the now line is.
Right-click the note in the staff view or Piano Roll view and see if it starts at something like measure 32, beat 4:942 instead of the first beat in the next measure, like measure 33, beat 1:000.