Did a City State give me a technology?

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Yesterday, while playing Civilization V: Brave New World game, I suddenly researched Refrigeration Technology, even though I was researching Atomic Theory (had 5 turns left on it).
How could this have happened?
I'm sure it wasn't from esponiage as I do not have any spies trying to steal technology from other civilizations.
Come to think of it, can City-States gift free technologies?
(I have all the policies in the Patreonage tree)
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What are the 5 city-states?
Historical city-states included Sumerian cities such as Uruk and Ur; Ancient Egyptian city-states, such as Thebes and Memphis; the Phoenician cities (such as Tyre and Sidon); the five Philistine city-states; the Berber city-states of the Garamantes; the city-states of ancient Greece (the poleis such as Athens, Sparta, ...What do you mean by city-state?
city-state, a political system consisting of an independent city having sovereignty over contiguous territory and serving as a centre and leader of political, economic, and cultural life.How many city-states were there?
There grew to be over 1,000 city-states in ancient Greece, but the main poleis were Ath\xedna (Athens), Sp\xe1rti (Sparta), K\xf3rinthos (Corinth), Th\xedva (Thebes), Siracusa (Syracuse), \xc9gina (Aegina), R\xf3dos (Rhodes), \xc1rgos, Er\xe9tria, and Elis.NEW CHANNEL ! Hood Tech 73 aka H.T.I.
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Images: Ketut Subiyanto, Sora Shimazaki, Pixabay, Sora Shimazaki