The Wolofs, kidnapped from their home in West Africa, led the first African slave revolt against Spanish rule in the Caribbean. Sources seem fairly evenly divided between 1521 and 1522 for the start of the revolt. I went with the more conservative estimate of 1522 in the book on page 31. In either case, it would have been only a few years before Esteban arrived on Hispaniola, so as a slave himself he was bound to hear about the island's slave unrest.
At the peak of the Wolof empire in the early 16th century, the Wolof army had 10,000 cavalry and 100,000 infantry. The Wolofs sent to Hispaniola on Portuguese slave ships were prisoners of war captured and sold by other African warring tribes. Each batch of newly arrived slaves included many battle-experienced Wolof warriors, and Spaniards blamed them for that first slave revolt — and also for many revolts afterward on Caribbean islands and later on the mainland Americas.
This blog's Oct. 13, 2018, article, "Africans from early history in the Americas," cites colonial officials calling the Wolofs "arrogant, disobedient, rebellious, and incorrigible." Any Wolof warrior would have have considered that high praise indeed and would be proud of such a reputation.
European milita quickly quelled that first slave revolt, but many Wolofs fled to the mountains and joined the forces of the young Taíno cacique, Enrique. Spaniards called him Enriquillo, and he was leading Hispaniola's native Taínos in a rebellion against Spanish colonists, with his forces reinforced by escaped African and Indian slaves.
On captured horses, the Wolofs became Enrique's cavalry and raided plantations, killing Spaniards and freeing slaves to join Enrique's Rebellion, which would last for about 15 years, from 1519 into 1533. Esteban would have heard worried Spaniards talking about Enrique's Rebellion.