Piper Jaffray analyst Nicole Miller Regan tells investors to add to Chipotle Mexican Grill positions even with the stock up 3%, or $13.44, to $485.20 post last night's earnings release.

The company reported "solid" Q1 earnings and reiterated its unit-level economic model, Regan tells investors in a research note. She believes a series of steady quarterly improvement is the next catalyst for the shares.

The analyst upped her price target for Chipotle to $530 from $483 and reiterates an Overweight rating on the name.