has it had it?
It could have, but it could also be sign of older plant tissue...just like with some other plants, different 'generation' of growth look different.
Leaning can be just a sign of it trying to reach what ever source of light is producing right wave length to support its growth...
BUT...it could be sign of rot too, which often start with cactuses from soil level and that would be case of over watering it.
If you can poke at the different looking area...and it is softer than the growth higher up...well, I would take it that 'is has had it'. The rot line will eventually creep up and the whole plant will give away, maybe even collapse under plant's own weight.
Is you cactus big one?