Ok, I feed Lilbug

Taste of the Wild Pacific Stream and she loves the food and I do too (I love that she loves it, I haven't tasted it or anything)

. Where I used to live (I moved the middle of last month

), I would buy her food from Feeder's Supply. Now, Feeder's Supply is around a hour away so I was just going to order it online to save myself the trip. Then, I found out they sell it at Tractor Supply Company which I was completely ecstatic about.
So, I've been staying with my mom this week and had to run back up where I live because Lilbug was almost out of food. I bought a bag and went on my merry little way. Last night I opened the bag and poured her some out and the food smelled pretty fresh (almost like any bag of food smells when you first open it) so decided to check the date. It has a Best By date of December 31st 2008. This food will last us a little over a month, most likely longer... I'm confused

on what to do.
I think I need to take it back but my mom thinks it will be fine.
I know the ins and outs of best by dates on people foods but don't know how they vary on dry dog food. So?!
Thanks in advance friends!