Well, giving a gift to your son might be a little over the top, but overall, I wouldn't have a problem with it. Maybe she is seeing it more as a day to celebrate men in general and the role they play in society, as good role models, etc. And every or almost every man, even teenagers, I would think , plays this role, or should be encouraged to play it, with their own children or nieces and nephews or siblings or children of friends or whatever, playing a father-like role.
The church I go to always emphasises this point, for both mother's day and father's day. All grown women get a little token the kids have made on mother's day and all the grown men get a little token on father's day, and the sermon is always about appriciating the female or male role models in our lives, respectively.
Now, if she didn't do the same thing for mother's day, for the women, then I might find that a little odd, but these ideas have to start somewhere and maybe she is intending to follow up with the same thing next year on mother's day for all the women.