MBN, the girdle thickness quoted is not too bad, with the "very thin" portion of it (0.9%) being on the top end of the very thin scale (very thin is 0.4-1.0, thin is 1.0-1.5%).
Extremely thin (knife edge, less than 0.4%) girdles are the ones you want to avoid. They will nick and chip over the years.
I would not turn down a stone just based on the "very thin" designation. Often on stones, the girdle will be mostly one size throughout, such as medium, with just one small portion transgressing into the very thin category. Often a "natural" which takes up a portion of the girdle will create this measurement, without being a threat to the durability of the diamond.
It's best always to have a second opinion when you get down to the nitty-gritty. Most jewelers will not object to this.
Rich, GG
Sarasota Gemological Laboratory