I had that issue a couple of times and the other guys hit it pretty much spot on. These days I'm bending a little bit at the loop and a little bit at the solder, and I have zero "creep." asA is right too, play with your needle stabilizer a bit. I found that having it rest on the bar just enough to keep it steady and keep the needles on the bottom of the tube reduces the ink creeping as well. Just my 2 cents.