First, the girl dropped 100 yuan to test your character. Now I know the answer.
Second, maybe girls know that your financial situation is not good and give you money in an acceptable way, which means a little pity for you.
Third, talking to you like this.
Fourth, she just thought you lost money and kindly reminded you.
Even without monitoring, others will see you pick up the money.
Suggestion: If you hear the news that others have lost their money, check and return it to the owner as soon as possible.
If the money is yours, you have nothing to worry about When you see that girl again, just say hello in a friendly way.