Ok, after getting her breed I went and looked around, and was forced to back peddle mildly.
I've changed my stance.
From minor researching, cavaliers can sometimes change after getting fixed, and the change is more obvious in males from some opinions. It's though by some that it might be genetic. Some cocker people, and a few golden people, also stated the same.
Again, this is very rare from what I had read, and from my prier dog knowledge (no cocker/springer/setter knowledge at all) but general dog stuff, I hadn't heard of it in my wanderings.
But it appears to be a rare but real thing, so it is in fact a possibly (sorry) that your springers coat changed after being fixed.
I agree fully with this persons take on it:
I think a spay causes dull and flyaway coat only occasionally and have seen little evidence to the contrary. Far more common is the dog's genes, being overweight, mediocre diet, poor coat care, overwashing and blowdrying, lack of needed oils/nutrition or just age. As a spay/neuter slightly lowers metabolism and therefore people easily overfeed and the dog gets overweight, I think poor coats are more the result of fat dogs and genetic predisposition myself, not the neuter.
And this one:
The coat changes are so minor (me: and so rarely happen) and don't even seem to affect many dogs that I'd never consider it a reason not to spay or neuter.
Don't forget, this was all quoted from select people on a open forum, so don't take any of it as sure proof or anything.
Last thing, trimming a dog's coat short can often cause it to grow back curly, fluff or cottony say a few people, was your springer trimmed around a month before?