Elliptical galaxies in Hickson Compact Groups (HCGs) are compared with their counterparts in the field. The stellar populations have been studied with two alternative models and reduction strategies to ensure the robustness of the results. Furthermore, great care has been taken to correct for emission contamination by Balmer lines, used to determine the ages of the galaxies. We find that, compared to the field, galaxies in HCGs are systematically older and more metal-poor, in agreement with previous works. For the first time, we show that the less massive galaxies in HCGs show an enhanced [Mg/Fe] abundance ratio compared to the field. This enhancement is interpreted as a relic of an event which truncated the galactic star formation, when the abundance ratio was still high. Recent hydrodynamical simulations predict such truncation after a galaxy merger, believed to be a common interaction in HCG environments.