Gas and lettuce

My bride and I have chuckled over the years about the time when for some reason we can't remember that lettuce went from 59 cents per head to well over $1.50. We largely had to either not buy lettuce or pay what we considered exorbitant prices. After a period of some months, the crisis in lettuce abated and the price came down to around 99 cents. To us, that meant the veggie was a bargain and we again bought it with nary a thought.
We are seeing the same thing in gasoline today. After buying a few tanksful at $3.49 per gallon, we have forgotten how neat it was to pay under $2.00 per gallon and now think nothing of filling up at $2.60 per.