I've found that even when everything is kept the same even with siblings some will require there cages tweaked a Lil different maybe this one requires 2 or 3 % more humidity. could even be when it was in shed heavy it rubbed something just a Lil to hard and put a hole in the old skin thus not letting part of the old skin separate like it should have thus causing the stuck shed it happens to everybody at some point in time even under perfect conditions I've had one die due to complications with a stuck shed (but it was a completely stuck shed took to vet and all 1 week to the day after seeing the vet it died)
i myself unless my snakes show signs on having problems or there is a whole bunch of unshed skin leave them be. only thing i do for them is spray them an extra time or 2 a day so it can work the old skin off as it moves around its cage and usually by the time it sheds again 99% of the stuck shed is gone. then when there eyes turn blue i put them in a smaller tote in-between wet towels then they shed all no problems