Defective innertubes ?

[Cuchilo]

After my spate of punctures with my gatorskins I swapped over to All condition armadillo . I bought new inner tubes so I had peace of mind that everything was fine .
After about a week a had a puncture A slow one so I checked the inner tube and tyre . Tyre was fine but the innertube had a round mark opposite the valve and it was leaking there . I took the tube back to the shop and they swapped it over .
Another week later and the same thing , again the innetube has a round patch opposite the valve and its leaking there . Exact same place .
Ive checked the tyre again thinking I must have missed something but to me I cant see how I would have put the tyre on in the exact same place again .
Ive put a spare innertube on now and noticed that this one doesn't have the round patch opposite the valve .
Anyone else ever had this problem ?

 

[screenman]

What size and what pressure are you using?

 

[Cuchilo]

700 x 20-25c . 115 PSI

 

[Cuchilo]

Round mark corresponding to the position of a spoke hole?

No Its on the other side of the tube where the valve is . Its like the valve has been stamped in too hard and left a mark on the other side of the tube .

 

[screenman]

Sorry not got a clue, I was thinking low pressure but obviously it is not.

 

[Cuchilo]

Im sure its a manufacturing fault as its too precise to be something in the tyre but I don't want to look like a nobber taking a second one back to the shop .

 

[Cuchilo]

The shop agreed it didn't look quite right and swapped it over . The new one has no marks near the valve so if this one goes flat then I am a nobber
and of course will pay for the two tubes that have been swapped over .