Question about a civil revolt to my side.

I started a game recently as Konian Hellan. I've beaten Macedon and had an alliance with Rome going well. However Segesta suddenly revolted to me and brought me to war with Rome. This was very surprising to me, as Segesta is a Ligurian city, and it had little contact with the Greeks other then trade (with the likely exception of Massalia) and it would make much more sense for them to join one of the Gaelic tribes or even the Lusotani (as the ligurians were thought to be of Iberian origin). Is there any historical reason for this, and if not then why do they join KH?