LaVorgna said he is monitoring that component. "My guess is we're going to see medical prices stabilize and start to trend higher. The year-over-year rate of health care is only up 0.8 percent," he said.
Another area he is watching for price increases is apparel in the CPI. "The rent is the biggest single piece. The wild card in the CPI is apparel prices. They've been soft and they bounced back in March. Apparel is one of the most volatile components, and that could determine whether the surprise is to the upside or downside," he said.
Traders are watching inflation readings careful because it would be a trigger for Fed interest rate hikes.
Read MoreBigger bets on normal inflation: Fed study
"I think the Fed has set the message that it's the PCE, not the CPI, that they snap attention to and (New York Fed President) Bill Dudley said 2 percent is a target not a ceiling … I think the Fed will be tolerating of an acceleration for a period of time," McCarthy said.
What else to watch
There are some major earnings Wednesday, including Macy's, Deere and Sony before the bell. Sodastream also reports, as does Pinnacle Foods. Cisco, Agilent and Sea World report after the close.