New Head Unit & Ohms

I recently bought a new radio head unit for my 2005 Nissan Altima. I've been doing my research on the head unit and speakers and I've found warnings here and there about using this head unit (rated at 4-8 ohms) with any speakers that aren't up to par. My car has 4 speakers that are 2 ohms each. They're stock. Everywhere else I look with replacing head units in this model of car has no mention of this issue. Is this a non-problem? If not, what are my options?