Airbus indications are notorious for fluctuating. They are sensitive little darlings.
At 100 psi I wouldn't be concerned nor should the pilot. Unless you are going to open the hydraulic line for any reason, that sort of stored pressure is acceptable.And that would be the reason you fully depressurize a system before breaking into into with the manual DP valve.
Anyway,its nothing for a pilot to worrying over, unless Airbus tells you different.