Hi Kat. Mine was "stuttering" quite a bit too last week, actually I think it was the driver's side mainly (only?), when it recently rained here.
I don't remember how long it's been since I had the dealership change my blades out, and admittedly I change wipers quite rarely because it doesn't rain all that much where I live, but it cannot have been more than a couple of years. I'd have to check.
What I did notice quite a while ago was that it didn't take long at all for the blades to lose their paint; it really took no time at all for this happen. It doesn't look good from inside the cabin, if one cared to look at them, but hey they're replaced often, so I just lived with them. So when I recently changed out my truck wipers with some Anco cheapies ($5) I got from Amazon, I made sure to treat the paint on the blades, I can't remember if I used sealant, or 303, or what. Unfortunately they seem to stutter a bit too.
So I have a pair of BMW wipers waiting to be installed, that I bought quite a while ago from Tischer, combined with a larger order, as I was thinking at the time I'm paying shipping already and I know I'll need them eventually. I will proably "seal" them too. (I did wonder about them losing effectiveness over time, maybe a bad purchasing decision.) Maybe I shouldn't seal them, to see if they are of better quality, at least the paint, but then what if they're not, I'd be a tad bummed, eh, I'll consider it.
Anyway, I guess my main suspicion is that the wiper blades that the dealership gave me are of very low quality, because I cannot remember, ever, having blades losing their paint, let alone in such a relatively short period of time (and this time on a well cared for car that spends most of its life in a garage). If the paint is so, so, so cheap like that, I wouldn't be surprised if they skimped on the rubber bit either.
I also use Meguiar's D120, though I have lots of Invisible Glass as well as Sprayway, and others, using Griot's polypropelene glass towels. I haven't clayed in a long time, and this includes paint, because the last couple of times I tried it was a waste of my time, the car is just too well cared for, for there to be any significant contaminants embedded. (It doesn't hurt that the sealant coats I use seem to last forever, and I attribute a lot of that to my extremely gentle wash technique, with choice of Griot's soap.)
I suspect that there is still residual Aquapel on the windshield from an application from last winter (possible?), because I think at 50+ mph, beads do just fly off without any need for using the wipers. At least that was the case pretty recently.