If it contains one of those flat batteries in it then this could be why the warning is on there - http://au.news.yahoo.com/a/12724575/a-battery-nearly-killed-our-son/
There's no battery with the card but can see how that would be dangerous.
Very odd. You would think they would make cards that are safe for 1 year olds!
When I buy a card I don't think about the small print!