The fragmentation of quasi-projectiles from the nuclear reaction ⁴⁰Ca+¹²C at 25 MeV per nucleon bombarding energy was used to produce alpha-emission sources. From a careful selection of these sources provided by a complete detection and from comparisons with models of sequential and simultaneous decays, evidence in favor of alpha-particle clustering from excited ¹⁶O, ²⁰Ne and ²⁴Mg is reported.