Had a similar problem with my wife's car. The tire dealer pulled it out and it was about 1/8" long and never pierced completely
We were still cautious enough to have it checked, as I did not want to pull it out (not being a run flat). That's my guess about your situation, since it shows no bubbles at all on a leak test.
ROAD HAZARD WARRANTY:
It seems some tire manufacturers have discontinued the road hazard part of their warranty. Tirerack indicates this on their site for Goodyear LS2. Search for that tire, click on "warranty
" and look for the .pdf called: "Warranty for replacement tires purchased on or after 11/01/12
". Note that tires purchased prior to that do include road hazard warranty. I checked with my dealer service manager also and he said that both Goodyear and Dunlop discontinued this this. In case some might be thinking they are covered for road hazard with newer X3's, I suggest checking this.
2013 x35i (Space Gray, MSport, CW/CWII, DHP, Premium, Premium Sound, Technology, BMW-Apps)
Retired: '09 C300 4Matic, '09 GTI, '06 750i, '05 C55, '04 R32, '03 M5, '02 GTI, '01 M5, '00 M-Coupe, '00 540i/6, '99 M3 Coupe, '98 M3 Coupe, '96 328i,... '86 4000 CS Quattro... too many to list.