Decrease in amount eaten

My daughter is 7 weeks old and over the past 5 days or so I have noticed a decrease in the amount she has eaten. She is formula fed, and she used to eat anywhere from 25-28 oz a day. She’s slowly been decreasing how much she has been eating a day and today she only ate 20.5 oz. do you think she just went through a growth spurt before and now she just doesn’t need as much, or do you think I should be concerned? She also has acid reflux that makes her fussy during feedings sometimes, but for the most part is controlled with Zantac.