Corrigenda for JACT Greek?

[Pathawi]

I hope this message finds you all well. I've been using the first edition of the JACT Reading Greek course pretty happily: I'm about halfway in, and I'm already beginning to find that I can make out bits of the material I'm interested in (not the Attic classics, but correspondence from the periphery of the Roman world). Since I'm now at the halfway point, and things are getting noticeably more difficult, I've decided to alternate between reading new lessons, and going back to old readings to make sure that I've retained what I've read. I went back to the first lesson, and was very rapidly struck my something that I missed the first time through:

The first reading is the story of an insurance scam, in which conmen Ἠγέστρατος and Ζηνόθεμις are attempting to sink a boat delivering cargo from Byzantium to Athens, so that they can collect on the insurance. Ζηνόθεμις is attempting to distract our hero, Δικαιόπολις and the captain from the sound of his partner in crime cutting a hole in the boat, so he keeps them on the deck pointing out the sites/sights of Athens. The captain loses his temper at being so obviously distracted from the sound he hears:

ΚΥΒΕΡΝΗΤΗΣ: ἄκουε, ὦ Ζηνόθεμι, καὶ μὴ λέγε 'ὡς καλά ἐστι τὰ ὲμπόρια.'

Shouldn't that ἐστι be ἐισι? Or am I missing something?