It is a widely known fact that red light makes cannabis stretch in veg. I think every book I've read on cannabis at least mentions this.
It might cause more stretching but that can easily be minimized by having enough light. I've vegged under MH and HPS. The HPS might stretch slightly more but if you have enough light it's really not much of an issue. I think light intensity is more of a factor with stretching than spectrum. You're better off worrying about light intensity than spectrum.
As to the OP's question, 4100K will work just fine for veg as long as they have enough watts. It doesn't matter what the spectrum is. Not enough light of any spectrum will cause plants to stretch. Given enough light it really doesn't matter what spectrum you use.
For the record, I currently veg under 6500K HO T5's. Prior to that I was using 3500K bulbs. I've also used a mix of 3500K and 6500K bulbs. The 6500K definitely produce plants with tighter nodes but the 3500K's are not that much different from my experience.
This plant was 14" and had 7 equally offset nodes before it started growing offset nodes and there were 3 of those so 10 nodes for an average of 1.4" between nodes. I've had the same growth under the 3500K bulbs. The amount of stretch difference between the 6500K and 3500K was less than 2".