I haven't had a gum graft but I had a "tooth lengthening" where I needed a crown but the underlying tooth wasn't "high" enough to allow it to be grabbed hold of. I too went to an endodontist and had a full root canal in that tooth and then the gum was cut and adjusted so when it healed the tooth could be used to build on. The procedure required 3-4 stitches is why I feel it might be similar.

I healed well but think my gums were in good shape to begin with. Took a week or two and I didn't have much pain or anything. I think it all just sounds worse than it is?