Could be, but not necessarily.
You're leaving out important information to make an informed decision.
If your wall is dry but bright and clean and free of marks, that could make it as fresh as yesterday...or somewhat longer. There's just not enough information.
But what if your wall was not only dry but chipping, peeling...and what if part of the wall is so old it's not even there...the wall itself has fallen over...???
Exactly my point. Why should it be embarrassing for those who think Mars is billions of years old that it doesn't take long for dust to turn red? CEH doesn't offer any reason to think that once it turned red, it wouldn't stay red for, well, billions of years.