I made homemade tamales for the first time yesterday and I think they turned out well, but I had a question about the masa I used. I bought a bag of masa sin preparar and it sat on my counter for 5 days before I used it. The sell-by date was the same date that I made the tamales, so I assumed it would be okay, but it did smell a little funny. I'm wondering if I should have kept it in the refrigerator or if it's okay to leave out on the counter. It wasn't refrigerated at the store.