So for the past year or so, Ive been working on my distorted vocals as backing for my band, and not to toot my own horn, but I feel I've been doing well. I'm using good technique to get a nice low sound and never feel any kind of pain unless I do it wrong for whatever reason (dehydrated, lazy, rushing) In which case I stop and take a wee break.

The problem I am encountering is that within the last year of said growling, I have been blessed with three fairly solid throat infections. More so and worse than I have ever had before. I have heard of this being likely from this kind of vocal style but do not have many details on it and was wondering if anyone could help out.

Is this a reaction from bad technique, or just my body getting confused or caught out by a new thing?
Has anyone else experienced this?
Will they stop as my body gets used to it? (The infections seem to be getting weaker, i think..)
This is quite possible. Even the best technique is going to impart some wear and tear on the voice. Little tweaks here and there can cause micro-tears on the tissue. When this happens you are left wide open to infection.

Frankly though, it's most likely coincidence. I know more than my share of harsh vocal users and don't see any more infections in them than the average fellow. I myself have been using almost exclusively harsh vocals for 4 years now with no increase in colds and such.

Something also to note: Because you are using your voice to do something you enjoy it's not only just a tool to communicate anymore. It's more of a part of who you are and therefore you will unconsiously wish to protect it more, thereby making you more sensitive to problems in the area. As such, you may have always (more or less) had colds like this and just cared less about them until now.

To answer your other questions:
-Reaction to bad tech? Could be but doesn't sound like it at all.
-Experienced? I've not seen this but at one point thought I was having more colds because I was paying closer attention.
-Get used to it?- Absolutely not. The cords themselves are merely mucous membrane folds. They are not muscles that can be worked out. The surrounding tissues can be strengthened and made more flexible but the cords themselves are basically static. How old are you though? Have you entered a new environment (ala university or high school)? This will always lead to more infections as your body runs across novel (for it) viruses and bacteria. Get lots of rest, fluids and take vitamins if you are deficient in anything you should see a dropoff over time.

Just some food for thought.

Finally, you seem to indeed be doing everything right. As long as it's not hurting then you are doing the best thing you can do to protect your voice. Also, make sure to get lots of rest as your cords heal remarkably better while you are relaxed and asleep.

Sorry for the book, but I get questions like these alot and it's helpful to get a better understanding of the whole picture, I feel.

Best of luck brudda!