Up it and see what she will take? If she’s not bringing it back up then it’s fine. Have a word with your health visitor if you’re worried. My first son would drain bottles, no issues. I was so concerned I was over feeding him. But after a while he evened out. If it was too much for her she would soon tell you
They do go through a growth spurt at 3 months so might be start of that if previously she was content?
Add to this she does not have reflux or colic