From memory that didn't happen, though others may know of examples. It should be noted that the effects of being half health/bloodied is already in 5e. Champion fighter gets regeneration when below half health, life cleric can Channel Divinity to heal up to half health, swarms deal less damage at half health (actually, this might be an example where a feature is lost in 4e).
These are the examples I can think of, there may be more in 5e, the only real difference is that they didn't want to call it bloodied.
Yeah, I was already thinking of the Champion fighter, but that is a single feature not gained until 18TH LEVEL, we we know 99.9% of players never reach unless they are playing a one-off or something.
Having a special thing happen for a few creatures is one thing, having a general "bloodied" condition is something else IMO.
I know a lot of people use it to describe a creature below half HP, but honestly with the abstract nature of HP I don't even think that is a good idea. The player can track how often he "hit" for "damage" already, so can learn to judge for themselves how "injured" a foe is.
Depending on the creature, clothing or armor worn, etc. even those tell-tale nicks and scraps and profuse sweating from becoming tired might not even be visible. Only (perhaps!) critical hits might have some signs, but even that is meaningless when it comes to HP. 5E doesn't
describe what a critical hit is narratively, only mechanically: roll natural 20 then roll double damage dice. It isn't like (the superior) d20 SW which actually tells you YOU ARE HIT, you couldn't avoid or mitigate the attack, and you are injured by a reduction in wound points.
A lot of players don't like death spirals, but in essence getting below half your HP should be a warning sign, not a trigger for awesomeness IMO.