Wasn't it said somewhere else that we had to use "er glad i" instead of "elsker" for family, friends and not romantic relationships? I've seen this a few times now and it's a bit confusing, and I'm starting to think the difference between the two aren't really that big, are they?
As an American learner, I was surprised to find Mothers Day to be celebrated on the second Sunday in February in Norway as well as many other European countries; it's an interesting difference.
So a little early for American standards but pretty late for Norwegian standards, I'd like to say: Gratulerer Med Morsdagen! (Hope that's correct)