agreed... the acro simply was dinged by a fish, hand or some other mechanical action.
The tissue dripping on stonies too at large is most often (most always really) a stress induced response. Make no mistake that water quality alone in tanks that are averaging the likes of more than one coral per ten gallons(!) are stressful. You would never see that kind of diversity on the reef suceeding for years if even months. You simply will not find 50, 30 or even 20 corals in a square meter... and that with massive dilution on the reef (quite unlike your pervasively degrading water quality in aquaria, weak water change schedule, et cetera). And if you did find 50 corals in a 100 gallon volumetric space on the eef... you would not find the same ones happily together 6, 12 and 24 months later. It just is unnatural and prohibitively competitive/non-conducive to natural settlement.
Planulation (asexual and sexual) instead is a conditioned reproductive event that occurs in time.
Bailout and tissue drips however are imperative reproductive strategies that are executed when the luxury of time (conditoning/seasonal influences/prepping) is not on their side.
That doesn't mean the colony will die by any means... but lets not entertain the illusion either that this coral is not embattled or stressed like the rest of our colonies in the noxious soup we call reef aquaria.
There is a reason why you do not have all the corals that you started with after 2 or 3 years
And we see the fruits of low species diversity tanks in the old European tanks. Really quite magnificent specimens in large displays that start with one fifth the number of corals that American, English/UK and Chinese aquarists typically use (too many, too fast, and too early in tank setups)
Sorry to be a buzzkill if so... but it is what it is. Polyp drips and bailouts are the (comparatively) fast and dirty reproductive strategies. Form follows function most always.