Brake line

My '99 Jeep Cherokee Sport (179,000 miles) suddenly lost brake fluid. I always check fluid levels before trips, had checked it two weeks prior to the total loss of fluid noticed only when the brakes became mushy. My mechanic found a hole in the brake line. Is this normal wear & tear or could someone have tampered with the line? I live in a neighborhood where this is a possibility.
Thanks for any advise.

I've had vehicles where the front brake line went bad and burst while coming to a stop sign - rubber does degrade over time, so it sounds like that's what happened to yours also.

However if you're uncertain, ask the mechanic to save the old brakeline - a small tear will be different from a cut.

The hole wasn't in any rubber - that part was OK - it was in the metal tubing that was slightly rusted, but not terribly. Any ideas how the hole might have gotten in a metal pipe? The vehicle is paved-road driven, not in salt-exposed environment (like snow treated roads or salt water off-road situations).

Big assumption on my part...sorry. Was the metal tubing corroded everywhere?

The hole wasn't in any rubber - that part was OK - it was in the metal tubing that was slightly rusted, but not terribly. Any ideas how the hole might have gotten in a metal pipe? The vehicle is paved-road driven, not in salt-exposed environment (like snow treated roads or salt water off-road situations).
Brake lines love to vibrate and shake (from normal road vibration) if they are not secured properly. If the line was not securly fastened down using all the factory clips then it simply could have vibrated and become fatigued or worn itself away by rubbing on something.

Also, it does not take much rust to blow a hole in the line. The line has more than 1000 psi in it during a hard stop which is enough to rupture rust- weakened metal.

A vandalized line is very obvious. IMHO if you are not sure, it probably was not the case. But blowing a brake line does happen with older vehicles.