I was putting my chains on this week and aired down my rears to install them. When I aired back up I detected a slight stream of air coming out of the stem after I put the core back in. It seemed to stop when I put the cap on and I checked my tire next day and it held air. Im thinking a new valve core may be in order as well. I have had them corrode in the past but the leaking one “looked” good. Tomorrow I’ll pick up some new cores.