ba.com and the app work automatically based on plotting the aircraft's movements forward and updating times as a guideline. The aircraft supposed to operate your flight on Monday (VIIX) couldn't land in St Lucia yesterday due to weather so is currently on the ground in Barbados. So that throws the plan for the next few days out of whack. BA will now work on changing around the plan so that other flights aren't impacted too much. Your flight isn't formally delayed until you get a text message and/or e-mail from BA with the proper details.