It's not unusual for electrolytic capacitors to go bad after 2 -3 years without reforming . Its depends on the manufacturer.For example Nichicon recommends no more than 2 years at 35C before forming is required.
This means they can't guarantee they are within specs, including leakage spec.
It doesn't mean the caps are "bad". They just need reforming to be in spec again. Reforming happens in-situ, when power is applied.
In practice, it means the leakage current is slightly more than specified for a few minutes to hours.
For example, it's completely normal that an assembled unit sits for 2-3 years before power is applied for the first time. You would have a huge epidemic of warranty issues if this timeframe was a problem.
If an elcap has gone bad enough to cause any issue (like excessive enough leakage current at first powerup to cause damage), after just 3 years, it's complete and total crap. No modern Nichicon or Panasonic cap does that.
Never seen that.
OTOH, in
30 (not 3) years old units, the result varies. Most of the time, they are fine, but the risk of caps blowing up or being severely out-of-spec (capacity and ESR), even after in-situ reforming, is considerable and varies a lot depending on manufacturers.