I found a hair clip in my boyfriend's room...should I be worried?

Well its definitely not mine so I'm not sure what to think. I asked him really calmly with no tone (not accusing) and I simply said who's is this..? and he said he Doesn't know and got a little deffensive but stopped and started being sweet after I said babe its not mine, has there been any other girls here? He claimed maybe its his brother's g/f's and his dad put it in his room thinking its mine...I trust him but should I be worried, and should I ask his brother's girlfriend if it is hers? thanks
I found a hair clip in my boyfriend's room...should I be worried?
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