How Far?

So, in classic Julie fashion, I got to the gas station and realized I did not have my purse with me. Minutes earlier I had seatbelted my six year old into his grandpa's van. The cousins are in town and everyone was going to go swimming. I had an errand to do so they were just going to go with Paw-paw. Of course I put my purse down to buckle the kid and forgot to pick it back up. So phone call to the paw-paw, and a trip home to meet him to get my purse and back to the gas station. This all took about 45 minutes. The first time I pulled in at the pump the price was $4.18/ gallon. When I got back, 45 minutes later, to the same pump, it was $4.23. I knew that gas prices fluctuated daily, I had no idea that now it's hourly.