You only get a message if a whole element has been replaced which removes one from the ledger.
Bringing existing elements up to full strength doesn't trigger a message but will use up replacement chits from the ledger.
Check round your forces, I'm guessing you have several units that need bringing up to full strength.
"Umbrellas will not be opened in the presence of the enemy." Duke of Wellington before the Battle of Waterloo, 1815.
"Top hats will not be worn in the Eighth Army" Field-Marshal Viscount Montgomery of Alamein K.G.