Any pain or redness? Most of the time infections are swollen, hot, red, and painful. Sometimes they aren't though.
I had that with some of the older GAULS gear. It was just my body reacting to whatever solvents they were using. Thought it was an infection, but never had any redness. Hurt like a bitch, was swollen, and hot. This happened with every, single, freaking injection.
Either it was my body reacting, or I was getting infections every time. Chances are, reaction for me.