It's not uncommon. May indicate that there are (as JK) said some deficiences, though amalgam toxicity can also cause bleeding gums and gum disease etc. I think anything that runs the system down could do the same. Not cleaning properly and/or flossing.

I wound up with receding gums after a course of antibiotics and they've never really come back to normal. I had a problem before that and was told I had periodontal gum disease anyway. Yet I had never noticed bleeding with brushing.

I take care of my teeth better now. I do use a fluoride toothpaste, much to some people's disagreement due to the problems of fluoride, but I find that Colgate total is the one that suits me best and seems to control the bacteria more and the staining. I use picksters (which is like a wire with a brush) and use that in place of dental floss. It is far better. You just have to order the right size, depending on the gaps between your teeth. As my teeth are tightly fitted together, I use one that fits. I think there has been an improvement. I recommend this.

At first thing may get a bit worse as your gums toughen up a bit from using the picksters, but it gets better again.

That plus diet/supplements maybe helpful and of course getting amalgams removed if that is the underlying problem.