Hygrophila polysperma leaf shape

I'm curious and can't find the answer to this online (possibly I'm not looking in the right place, but I googled for ages last night...)
I purchased a few bunches of Hygro polysperma from my LFS, brought it home, planted it, and it's doing really well (I believe it's actually considered a weed in it's native habitat, so no wonder it grows like crazy, lol).
My question relates to the size/shape of the leaves. When I got the plant, the leaves were about 1/4" wide x 1" long, about the size of a small almond. After living in my tank for a few weeks, all the plant's new leaves are 1/2" wide and 2.5 - 3" long. They're also wavy.
Is this a response to more or less light than the plant had before I got it? Is it a response to more or less fertilizer? Overall, is it a good or bad sign that the plant feels the need to put out these gigantic leaves? It's very attractive, and I don't mind it one bit, I'm just curious as to why it's changed so much.
Lighting is (new) 2.5WPG 9325K CF on a 24" deep tank, temp is 80F, pH 6.6, KH ~80ppm, DIY CO2. All the fertilization and other details can be found by clicking on my signature if you need them.

It looks like your Hygro and mine are fairly similar looking, but the difference between what I (and you) have in the tank and what I bought really is huge - hope someone out there knows why, I'm SO curious.
I actually read on the Krib last night that this plant IS a weed, and it's been banned in parts of the US.

I was actually saying that Scottracy's and mine look alike - that's what mine looks like NOW, however it's vastly different from the way it looked in the store when I bought it. It looks like a completely different plant - it's pretty goofy looking in my tank right now, the bottoms are small-leaved, skinny stemmed little things, and the tops are HUGE!
If the larger leaves and rediculous growth rate mean it's happy, then that's great! I'm just getting ready to prune for the very first time, psyching myself up (there's a lot of hygro in there to prune, lol).
Part of what I was wondering was if it was putting out larger leaves in an attempt to get more light; I was hoping this wasn't a sign that I need to provide more light (goodness knows I'm fertilizing as fast as I can and there's loads of CO2 to go around, so not having enough light is the only thing I could think of that might be hurting the plants).
Since several people say theirs looks like this, I'm going to take it as a sign that the plant isn't miserable. I'm still laughing at myself for paying $4.95 a bunch for a pest plant, but no one can deny that it's pretty