Yes, wine storage conditions matter even for port!  Following is a very sad story of how critical this issue is. 

Recently we got a chance to try two 1980 vintage ports together that had been stored in very different conditions.  The difference between the two wines was a revelation to me!

We had been given a wonderful vintage port for our wedding and had been saving it (in our wine cellar) for a few months.   The Quinta do Noval Nacional 1980 had been bought at a local store, as tore that is known for excellent prices but not necessarily the best storage conditions.