Robert Kaplan, president of the U.S. Federal Reserve Bank of Dallas.

Weak recent inflation readings are a worry and suggest the Federal Reserve will make only "uneven" and slow progress toward its 2-percent goal, Dallas Fed President Robert Kaplan said on Wednesday.

Speaking with reporters, he added however that "price pressures are likely building" given U.S. unemployment has fallen, and noted that price data for April suggested a "return to trend" for inflation.