nope. I've used a variety of fittings, copper, plastic way back in the day, now compressions. I've used new and 2nd hand blocks, with and without dyes in the water etc.
I stopped being serious about watercooling probably 4 years ago and ever since I've been using pretty basic setups with deionised water and nothing else, I've even drained deionised water out of the loop back into the bottle and used it again when I've done the odd gpu upgrade etc.
I've literally never had an issue. I'm sure the problem exists and all that but I've been seriously careless and never ever had an issue with nasties. I've had issues with practically everything else but never anything alive in there!
