The very fact that you were able to register for 4 of these implies that they're not current, because on current Stay X Get Y promos, you can only register for one and then it locks you out of all the others.

In case you're not aware, randomly entering codes is likely to get you promos that are years old, because for whatever reason Priority Club doesn't tend to ever remove them. So without some research to see if they've ever been mentioned before (which I presume is what DanTheMan does), you can't tell whether they're current (but they're more likely than not to be old).