I thought about your post quite a bit before answering. Relationships with in-laws can be delicate sometimes and if they have a good relationship, you definitely don’t want to offend the woman who raised your husband.
I’ve decided that the truth is the best answer.
You to in-laws: Have you read anything about toys from Amazon having lead based paint on them? I love your present and think it’s super cute, but I read this article and it scared me a little. Would you be offended if I put this toy away for a little while? Just until she’s old enough to stop putting everything in her mouth?
Make sure you have an article cued up on your phone to show them. Listen to their response, and practice feel, felt found.