Interesting: our visa was stamped on the way in, but some US citizens had the entry stamp in their passport pages. On departure from José Marti today, TWO departure stamps, two visa pages apart, were stamped into our US passports.

Flying to Cuba, we used SY8830 (Sun Country) MIA-HAV. For our return, arriving at MIA on AA 9413 (both flights were with Boeing 737-800s), we used Global Entry - usual receipt, taken at Customs. Our flight number and origin were on the receipt, but we were not asked any questions and we were street side in very short order.