Where in the United States are you?
What is the soil this is growing in like?

It could be sunburn. The rest of that leaf and the other one below look okay.

I'm in Northern California. As for the soil I'm not completely sure what it is. I know it has peat moss and some rice hole in it.

give us a pic of the whole ..

all plant shed leaves.. either due to age.. or stress .. sometimes we just pluck them off .. sometimes we see something that needs to be addressed ...

but for sure.. we can not tell much from a pic of one leaf ...

what just changed in its life??? .. did you just buy it.. move it.. how do you water.. etc ... give us some facts about the plant besides the pic of one leaf ... and dont forget... with winter coming.. the declination of the sun has changed.. is it now in more sun than previously .... [BTW .. is it indoors or out???]

and if that is all the damage.. just snip off that leaf .. and move on ...

ken