Months of steadily declining prices have given investors the sense that inflation is on a linear, downward trend. But inflation is more complex than it initially seemed and could surprise markets still.

Economists are expecting January’s consumer price index to rise 0.4% on a monthly basis — that’s a jump from December’s -0.1% figure, which means that prices actually fell. So far, market chatter is that service inflation — the price of travel, dining out and hospitality, for example — has proven more persistent than goods inflation, largely because of an extremely tight labor market.

But logistic managers are warning that the supply chain is clogging up again, which could contribute to higher prices for goods. “Late fees and warehouse fees are passed onto the consumer, which is why we are not seeing products fall as much as they should,” said Paul Brashier, vice president of drayage and intermodal for ITS Logistics.

Nonetheless, markets showed optimism on Monday. The Dow rose 1.11%, the S&P 500 climbed 1.14% and the Nasdaq Composite advanced 1.48%. Investors may have been hoping for a “Goldilocks-like mix of industrial production recovery and falling inflation,” said Ray Farris of Credit Suisse in a Monday note. Time will tell if that comfortable narrative of disinflation — and the defiant optimism in the markets — hold up.