The Stoics do not consider remorse for guilt an appropriate moral sentiment (see below), as we have learned to do in our Judeo-Christian culture. According to Eric Dodds, writing in a chapter of his The Greeks and the Irrational [via rougeclassicism], "From Shame-Culture to Guilt-Culture," a sense of religious guilt appears only late in the Classical period.

"Strictly speaking, the archaic sense of guilt becomes a sense of sin only as a result of what Kardiner [45] calls the "internalising" of conscience—a phenomenon which appears late and uncertainly in the Hellenic world, and does not become common until long after secular law began to recognize the importance of motive [46]" (36-7).

[46] "[...] It is, I think, significant that side by side with the old objective words for religious guilt ([agos, miasma]) we meet for the first time in the later years of the fifth century a term for the consciousness of such guilt (whether as a scruple about incurring it or as remorse for guilt already incurred). This term is [enthumion] (or [enthumia], Thuc. 5.16.1), a word long in use to describe anything "weighing on one's spirits," but used by Herodotus, Thucydides, Antiphon, Sophocles, and Euripides with specific reference to the sense of religious guilt (Wilamowitz on Heracles 722; Hatch, Harv. Stud. in Class. Phil. 19.172 ff.). The specific usage is practically confined to this particular period; it vanished, as Wilamowitz says, with the decline of the old beliefs" (55).

In Liddell & Scott's A Greek-English Lexicon (1968, pg. 567) I found citations of the works of the authors that Dodds refers to where [enthumion] is being used . The term "guilt" is not the translation, there, but that seems to be the meaning intended, or very close to it.