What kind of rims? What kind of rim strip?

Some types of rim strips can shift from side-to-side during the tire changing process. If that leaves the tiniest little arc of unprotected spoke hole exposed your tire pressure will force your inner tube against that metal edge and, over a period of time - usually not immediately, make a hole in your inner tube. It looks to me like that's what may have happened to you.

Unless I have tires that are real hard to fit, Velox is my preferred rim strip, preferably wide enough to fill the rim space all the way from flange-to-flange.