I had nutrients ($600 worth) in a storage unit for most of a winter season. I know that one 4L had froze (was half full), but the rest had no signs of being bad (unopened). Still using them and apparently I have not any issues.
On second thought - I recently purchased new AN Connoisseur and didn't notice any difference from the stuff that was in storage.
Uh... anyways, you should check to see if the nutrient solution looks any different. Like if its slushy or has odd sediment or smells bad. If you're sure it didn't freeze, you should have nothing to worry about.