The Albiceleste are currently readying themselves for friendly meetings with Guatemala and Colombia.
They will be taking in those fixtures without that talismanic skipper, with Messi having been handed a well-earned rest on the back of another frustrating World Cup campaign with his country.
The 31-year-old forward is yet to reveal whether he will be returning to the fold, but an iconic jersey is being held back for him.
"I don't understand why it's not being used now. I haven't asked. I haven't inquired. I had no idea that it wasn't going to be used.
"In all the friendlies, it has always been available. Probably, for some reason, it will not be used now. I just found out."
Romero added on Messi’s international future: "If Leo returns, it's normal that he is the owner of the No.10 and the captain's armband - no one on the inside or outside has any doubt about that.
"But if it's a number that is available for a friendly and Leo is not here, then anyone can use it. We already know that if he is here, it will be his, so then there's no problem."
Interim Argentina coach Lionel Scaloni has revealed that Ajax defender Nico Tagliafico will be taking the captain’s armband for a meeting with Guatemala in Los Angeles.
Messi will fill that role again if he opts to return in the future and add to his haul of 128 caps.
There has been no indication as yet that he will be heading into international retirement, with his national side prepared to wait as long as it takes for a talismanic figure to make a decision.
Scaloni has said of the five-time Ballon d’Or winner and his plans: “I think it's clear, we spoke with him and we'll see on the next list if he comes back or not.
"I'm sure we'll see what happens in the future."