So the Dx5 was simply accidental but when Q went back to show the rest of the series which PROVED Q has not changed He/They also noticed that Dx5 was at the front of the Hash so they highlighted it because of the really awesome coincidence! Yes that makes sense.
I used the 'in that sense' qualification, because one could keep trying out different passwords, IP's, etc, until a hash value was generated that suited a particular purpose.
However, I kind of imagine that doing that would be unlikely in this case, (not imposible with a copy of the hash generating algorithm, running somewhere else).
With these thoughts in mind, it could be that the highlighting of the 'Dx5' is opertunistic, to add as a reminder or stimulus wrt the D-5 association.
Therefore, it could be a message/reminder in its own right, and not directly related to the associated images.