Jonathan, if you have a SWCG, this is about normal if you keep your TA over 100. Waterbear, chem_geek and PatL have posts on this. If you lower your TA to the ~70ppm range, the outgassing causing the pH creep will minimize so you would need to use less acid If you have a plaster or pebbletech pool, you may need to adjust the calcium down to allow for this.

I'm far from an expert on this, but it's what I remember