Probably the relief valve tripped on temperature, just what it was
supposed to do. With the relief valve that old, yes I would replace
it. The water heater should be fine. If it ever leaks, the water will
only wet the garage floor. If it were in the house, or where the water
could damage the structure, I would want an emergency pan under it
piped to the outside.

DO NOT put a hose on the relief valve discharge pipe, that would
restrict flow. It should be piped to the outside with an elbow turned
down. The relief valve discharge discharge should be piped FULL SIZE,
with no more than 25 feet of length and no more than 4 elbows in the
length (Old code but a good idea). If the relief valve discharges on
the floor, the pipe should terminate no more than 6" above the floor to
reduce spalshing.

Stretch