I've gotten about 6 flats in the past week that had me scratching my head.

They have all been outside punctures. I quadruple checked the rim tape just to be sure, no problems. They were kinda random, not happening immediately, not in the same areas of road, and no slow leaks. At each tube change, I used my fingers to check every surface of the rim and the tire and nothing seemed odd.

So, in a bout of frustration last night, I pulled the tire completely off and examined it and the rim under great lighting. I finally found a 3-4mm gash in my tire that was unnoticeable by finger touch with the tire not under pressure. Sure enough, with the tire under pressure, the gash opened ever so slightly and evidently has been causing me problems.

I've had a pair of junky cheng shin $5 tires pulled off an old bike that has long since been sold. I threw one of those on while I'm waiting my RibMo's in the mail to replace the stock Specialized tires that came on my secteur. The funny thing is that I have been considering tossing the cheng shins for a while but for some reason never got around to it.