Not interested in bottle

My 3 month old is fed every 3-4 hours 4 oz. recently she has been pushing her bottle out of her mouth and wanting no more than 1-2 oz at a time. Before bedtime she will drink 5-6 oz but that’s the most and only time I can get her to drink. I will try to feed her her normal 4 oz but after 2 she is spitting it out and pushing her bottle out of her mouth. Other than that, she is perfectly fine and playing. Her usual self. Why could this be?