He should say, but for her sake.
Technically, we know of the rule that Hanosen Matana Lachaveiro Tzarich Lehodio — if you give a freind a present you should let him know. However he would probably feel silly, as if he were trying to solicit a compliment. On the other hand, though, considering that this would give her burden of having to be on alert, and she feels terrible whenever she notices it too late, it would be kind of him to just let her know.
Sounds complicated?