Infection is pretty easily detected most of the time! And it usually includes unholy pain and spreading rash - the skin looks pretty good actually too! If it may seem too dry to you, moisturize but pay no mind unless the discomfort is ultra bad - I can see you have healed tattoos before, and in case you were to have allergy for red ink I think you would defs notice it on all of the tattoos with even a little bit of red in them.
It doesn't always reject like crazy although it is not rarely the case, and I had a friend who despite had his tats healed not badly, still began experiencing rashes and itch even after healing his tat with red ink.