There are several possibilities:

The most common is an improperly installed tube. If you have even a little bit of tube pinched under the tire bead, it will sometimes blow out immediately and sometimes it will wait awhile before it blows out.

The psi rateing on your tire is only 50% of the equation. What's the psi rateing on your RIM? Usually nobody knows. They just assume it's OK. Keep in mind that rims don't improve with age. Brake use eventually wears at the rims and allow the flanges to flare outward.