To answer my own question, the vet said it's not uncommon for this to happen
with older cats.

Two nail clippings ago I noticed that Tiggy's claws on a few "fingers" have
gotten really thick. I didn't think too much of it the first time I clipped
them. I thought maybe she was getting ready to shed the outer nail like they
do periodically. When I clipped them the next time and they were still thick
I got a little concerned. She has one front paw that the nails are pretty
normal and the other are mostly thick. There isn't anything unusual about
the color. Is this normal in older cats? Fungus infection maybe?

She has a vet appt. next Thurs. (along with the rest of them) but just
wondering if anyone had encountered this before.

Wendy