Baby started to not finish whole bottle?

B

So my little one has been sick which I figured she would Maby lose a little bit of her appetite but this is kinda weird to me. She typically eats 6oz and I mean every last drop or she wouldn’t give the bottle up. Now she’ll drink all and leave just under an oz and play with the bottle/chew on the nipple. So this morning when she woke for her mid night feed I backed it off to 4oz thinking Maby she didn’t want as much and she did the same thing. Just under an oz left and then she starts to play with it. I tried to guide her and she just slapped the bottle around and shook her head. Anyone know why this may be or had a little one who did the same?