Where on the tube was the hole? Inside or outside? If your rim liner isn't covering your spoke holes completely, the tube will expand into the spoke hole (and they usually have sharp edges) and will eventually result in a flat. I went for a 50+ mile ride to the beach and back a couple of years ago. Loaded my bike in the back of my Pathfinder and started home. pffssttt. My tire goes flat. Crappy rim liners were to blame. Use Velox rim tape if you aren't already...