In my experience the silk core Velvets, including Animas, take at least a couple of weeks (if not more) to stop stretching. As for the G string, the Anima set is unusual among Velvets in having a different winding for the G. It's just the way it is, nothing wrong with your string (although as a warning Anima Gs have been known to break - one did for me, for no reason it just slackened, but Nuno at Velvets replaced it with a new one free of charge)
Edit: as Misterbadger points out below, the Garbo G has the same type of winding. My bad, I thought it was just the Anima G
Clarkybass I'm quoting you because you asked me how I'm liking the Animas in a message a few days ago. I wanted to give my review.
I've had the strings on for about 3 weeks now (or maybe 3 days. I never know haha). I really like them. I put them on because I wanted a lower tension string to help me through an injury.
I'll start with the Pros:
They amplify well. I heard bad things about amplifying plain gut strings and was worried that these might be the same. To my luck they sound great through the amp. I got may compliments on how my setup sounded.
They sound big and full with little effort. I love playing on spirocores for the reliability of them but had to work a little bit to get a full "big" sound. I am able to use a lighter technique on my right hand and still get that big bottom from these strings. They're nice and thumpy but also have good sustain. I hear the type of tone on those old paul chambers records. I can get what I call his staccato sound as well as his sustaining sound. (What I mean by that is I have found that his playing on Workin Cookin etc sound a little more staccato where his playing on Kind of Blue seems to flow more).
I also love the gauge of the D/G. I think that allows for a big tone to be pulled from them.
Cons:
Tension: The tension hasn't changed for me. I have come to the conclusion that this is due to my bass setup. I'll need to get that looked at eventually. While the tension is not lower than spirocores (I feel) I am able to play lighter and get a bigger sound, so I don't use as much effort. Thats a good thing at least.
The E string isn't as powerful as the Spiro that I am in love with, but it blends with the set great. I noticed that there are some winding issues near the nut (around F/F#) I'm gonna be keeping an eye on that and if it gets worse I'm hoping Velvet will replace it.
My only other complaint is that they are still stretching. The first day it was crazy and has gotten better, but I can't go 20 minuets of playing (2/3 songs at a restaurant standards gig) without having to retune the bass. Its not horrible but I'm hoping this stops in a few weeks.
I would say that I am very happy with the Animas and as long as I don't experience the quality issues I've read so much about, I would love to stick with them. I can feel myself slowly moving towards the world of Gut… someone send help quick!