probably not. leathers do this once in a while. both of mine leathers (Toadstool and a Finger Leather variant) do this from time to time. my finger leather turns yellow at the tips from time to time as well.
leathers will look like theyre going under, and then perk up a few days later, they do this to shead their slime coats. i even think they know that they can sulk, they are very tempermental. sometimes one of my leathers will open up, and the other will stay closed. then a few hours later theyre both fine. then the 'healthy' one will start look sorry for itself.... ect. my toadstool can also range in size from 4" across, to almost 10". depending on its mood.
keep up the WC's and check params as normal to make sure theres nothing going on with your water. then just keep an eye on it. if it starts to look grey and deflated, its getting ready to shead. as soon as it starts, keep an eye out for any slime floating around the tank, remove it as it is poisonous to other corals. in a few days it will be back to normal. but if theres no change after about a week, you may wanna think about cutting the bad bits off.
another thing to consider is chemical warfare. leathers have a pretty potent punch, they can and have wiped out tanks. maybe yours are fighting for real estate. they look like theyre touching, id cut one and move it to another spot. i leave a few inches bare after the inflated size to avoid this.
how long have you had it? is it a new addition/recent purchase? my finger leather looked like it was toast for about 2 weeks after i bought it home. it even looked like it was rotting. now its fine.
