When you first get the tattoo, this kind of reaction is normal, but a
month after it has healed? Well, I don't think it's typical, but since
you said you stand a lot it could be that, that is slowing down the
internal healing process. If you don't have any redness around the
area, and the skin surface doesn't feel hot, or extra warm to the
touch, then I think there's probably no infection. If it continues,
and bothers you, then I'd have it checked just for your own peace of
mind.
Mark