It should be fine. You could try reducing the WC
amount to 30% and performing it 2x a week until the pH returns to what you are used to seeing.
Interestingly, this kind of change sometimes induces spawning in certain fish such as tetras.
You could try putting some tap water in a glass and letting is sit overnight to see if the pH is the same. Ditto with the tank; take another reading tomorrow.
I don't check my pH anymore. When I did, I would see 0.5-1.0 swings on a daily basis; it's a planted tank and CO2
injection can influence pH readings.