Egg whites sour smell?

I've been using the Lucerne brand Liquid egg (egg whites) for 3 years now and the past 3 or 4 cartons have had a strange kind of sour smell. The first time I could tell they looked off when I poured them out of the pan, after that I've noticed they have a weird smell as soon as I opened the new carton so I'm starting to think maybe the recipe changed or something and I'm just convincing myself of the smell. I can't tell if they taste bad because the smell is present. Anyone else notice this? It's not a sulfuric smell like bad eggs normally have, just sour..... I've icked myself out so badly pls tell me if I'm crazy.