Cat: Adult Growth Spurt?

I brought my cat in to this apartment a year ago. She was four years old, and she was tiny thing. I mean, she barely looked larger than kitten-size. She never got along with other cats, and I moved out of a household with three other cats. She was stressed out there, and before that she was a rescue and spent about a year in a cage because they couldn't place her in any home with other cats.

So, after a year of having a place to herself, and being fed well, I just noticed today: she's grown. I don't mean she's gotten fatter, either. She is now a full-size cat.

As long as I've been around cats, I never knew before: they can have a growth spurt well into adulthood. What's funnier is, she had at least two litters of kittens, because she was found with a litter and pregnant with another one. She was barely more than kitten-size herself.

I just wanted to report: there's yet another reason to find cats creepy.

Scratch my neck, or I'm going for your throat