My dog, Tinkerbell had her spaying on January 25, 2007. Ever since she's had this knot on her stomach. I asked the vet about it when I got her stiches out and he mentioned a busted blood vessel or something since it was red and swollen. Since then the redness has went away but the knot is still there. She doesn't act like it hurts or anything when I touch it and acts as if nothing is wrong. SHould I be concerned? Any input would be appreciated.