it is not uncommon.. to lose the oldest frond or two as you move into winter ... its usually not hard to tell the new growth from the oldest growth ...

i can not tell such from your pix ...

if they are the oldest.. just remove them ...

ken

I lost one I had for years last year, nice big one. I felt awful. Only thing I could think I did was to transplant in February and increase the soil volume. I have read that they are temperamental if too moist in winter (it was fine when the soil was dryish in winter).

It's since been replaced by four smaller ones, I love this species!