Can I leave my cake out of the fridge even if the frosting has milk/cream in it?

So yeah, I made a chocolate cinnamon cake today and I added cream and some milk to the frosting. Is it ok if I leave it outside of the fridge (at room temperature), or would I need to stick it in the fridge because it has milk/cream in? I only used a small amount (just over 2 tablespoon), so would that matter? I know that when you use cream cheese or anything like that it needs to be kept in the fridge. This is why I am asking, and also because my fridge is pretty full up so would require tremendous effort to find space.

Thanks.

Here is the recipe if anyone was curious. I would recommend it :D http://www.taste.com.au/recipes/8825/chocolate+cinnamon+cake