Can't think of any reason the rim strip would be a factor - maybe for a pinhole leak but not a blowout unless it was crooked and interfered with the bead-rim interface.

I've seen a dozen or so tire explosions while the bikes were parked - usually a sidewall failure but sometimes a bead blowoff. It's certainly more likely to happen with higher pressures and warmer temperatures but sometimes it happens for no discernable reason at all. Could be you got the new tube pinched in the new tire and it held on just long enough to make it a mystery.