Probably worried about Cirno being a 'bad influence' again.
There's seems to be a theme where Ran hate's Cirno
Updated
It looks like Cirno's temperature has gone down further.Okaaay.What a relief.I won't allow you to visit her!Chen! Now's the time to go check up on her!Vrrrm VrrrmHold iiittt!Whoa!"Now, Chen!"Gaaah!