I have said as much to my wife, but my children are too young to really understand. Besides, it's meant to be a consolation to them when I'm no longer around.
If there's one thing I've learned as a parent (particularly around language but also around empathy) it's the kids understand much earlier than we often give them credit. Telling your 1 or 2-year old you love them is absolutely received because they know more language than they can project, but also because the tone conveys love more than the words. Tell them often! :)