This question does not have to do with home brewing but I figured someone here would be able to answer.
It does seem to bubble very slightly when poured out but tastes fine. Just wondering if there is a big 'don't do that' attached to this.
Putting strong spirits in the freezer should not harm them. The solubility of air gases increases at low temperature, which is why you see bubbles as it warms up.
Drinks with a lower alcohol content will be affected in the freezer. There is potential to freeze water out of anything with an alcohol content of 28% or lower. Many people use the freezer to increase the alcohol content of their home brew in UK, by freezing water out of it - the alcohol stays in the liquid portion.
I stored my entire stock of liquor outside during an Ohio winter for about a week, just took the cap off my previously unopended bottle of Jack Daniels and soon as I took a shot it had a terrible spoiled taste, and i mean I have old no. 7 tatooed on my arm but I just cant drink anymore of it(and sadly its the big 1.75 ltr)