Convince me it's useful to do so, and I will.
Scum would love to know what item I got, I don't see the benefit for town though.
Let's say the Item Giver player (presumably Town) has been giving out items all game, but by the nature of the game, items have gone to both scum and town players. That means it's pretty likely a scum player got an item. If that's the case, then you're only hurting Town by not talking about it.
Furthermore:
An entire group staying quiet about getting a secret item could be that nobody wants to be the one person to speak up first. Fine.
However, once someone does bring it up, the psychology of the situation changes.
Maybe you're the one good guy who decided to finally bring it up, in hopes that the Item Giver will acknowledge you, and by the same token, acknowledge that those who haven't said anything could be the shadowy scum players with something to hide.
Or, maybe you're one of the scum players who decided to bring up the item situation, from your relatively safe position in the game, to see who else brings it up - depending on what the item does, this could give you an idea of who to target from now on.
By bringing up the item at all, you've already done most of the work.