All were wondering
In their hearts
Was he perhaps
Προσδοκῶντος δὲ τοῦ λαοῦ καὶ διαλογιζομένων πάντων ἐν ταῖς καρδίαις αὐτῶν περὶ τοῦ Ἰωάνου, μή ποτε αὐτὸς εἴη ὁ Χριστός,
This question about John the Baptist being the Messiah can be found in John, chapter 1:25, where the Pharisees asked this question. Here Luke said that the people were full of expectations (Προσδοκῶντος δὲ τοῦ λαοῦ). All were questioning or wondering in their hearts concerning John (καὶ διαλογιζομένων πάντων ἐν ταῖς καρδίαις αὐτῶν περὶ τοῦ Ἰωάνου). Was he perhaps the Christ, the Messiah (μή ποτε αὐτὸς εἴη ὁ Χριστός)? In other words, the question was not explicitly stated, but only thought about. They were wondering if John the Baptist, the son of Zechariah, was the expected Messiah or Christ.