Not sure why you hung on to old tubes in new tyres? That's most likely to be the issue.
The prime degrader of tyre and tube rubber is age, closely followed by ultra violet light. Add heat, wear and extremes of temperature and assuming there are no chafing or sharp edges inside the tyre carcass, you're on a loser!
It's hard to diagnose the cause remotely without seeing the point at which the tube gave way. If the pressures were too low, there would be evidence of chafing or movement around the places of conflict & I doubt the tyre fitter would be looking that close for you..
