The price of gas plummeted in late 2014 and economists were talking about all the ways Americans would spend their extra gas savings.

It turns out, they're just saving it.

A note from Deutsche Bank on Monday notes that December retail sales beat expectations, but figures for both January and February have declined.

The firm writes:

But what about the windfall from lower gas prices? Wasn’t this supposed to offset these other concerns? Gas prices have rebounded to $2.45 from the low of $2.04 in January, but are still down 29.7% y/y in March. What are consumers doing with the extra money? [The chart] appears to show that much of the benefit from lower gas prices is being saved.

And so what next? Deutsche Bank says it expects comparable sales to accelerate after a weak first quarter as some of the increased savings get spent by consumers.

Another reminder that while economic theory may assume rational actors, we're just people after all.