First time flying Frontier on a route that is only 3x a week it seems. One flight a day. Original flight time was 3pm, I have a printed itinerary that shows this as I did this at the airport to save on the bogus online ticketing fee.

Fast forward a few months as I’m nearing my flight date, and the time is now 1:30pm. I checked my emails, no notice at all.

Make sure you monitor your bookings! A few minutes change here and there I can understand, 90 minutes becomes significant. Luckily it still works, but if it had gone the other direction (later) it could have been a mess.