Glad she has had the stitches out now, poor girl
Is there a lump where she was scratching at all? It's not that common but I have seen reactions to antibiotic jabs given under the skin of the scruff during a spay.
As for the dissolvabl sutures, it's a difficult one, they are a lot fiddlier and take longer to do so some vets prefer not to, particularly if the op has taken longer to do. Another factor is that, there is a lot more 'foreign material' sitting under the skin and it can cause a local tissue reaction in some cats. We generally only do it on request, and for the wild TNR cats of course.