what's four cents?

Last night while running errands with the BF, we stopped by the gas station to fill up my car. As I started pumping the gas, I noticed that gas was a little more expensive than I remember it being (but still far less than it had been a few weeks ago! I'm very thankful for that!) I realized that we were at a different gas station than the one we used earlier (for his car) so I asked him how much gas was there...turns out it was 4 cents cheaper. Rather than fill the whole tank up, I actually stopped 3 gallons in. I don't plan on using the car until Monday morning and I can stop by before work, especially since that station is on the way. Or I can wait until Monday afternoon, and gas up at Costco for even less.

Was it worth it to wait to save 4cents/gallon?