Possible mold in rental unit

[John Chang]

Hi all, I am new to this forum so forgive me if this has been asked before. I have a rental property in Costa Mesa, CA and a tenant claimed that after she cleaned, her carpeted floors in her room were wet and she was worried about mold being under the carpet and in the walls. I checked and her bathtub needed caulking so I fixed that but she said that would would now like new floors because she is worried about mold. I bought her a damprid to get rid of excess moisture and told her she should have opened her windows to ventilate and that she should have told me right when she noticed, but she waited several days until she finally paid her rent, after it was past due. I felt the floors and they felt dry to me, so I told her I would think about it. This tenant never pays on time and any time I tell her she needs to pay on time, she has a complaint about something in the unit being broken, or needing something to be done in her unit, etc., so I'm wondering if I can tell her to pay for a mold check by a professional is she is concerned about it.  Everytime she has mentioned something needing to be fixed, I have done it, but I don't know if she just wants new floorings, so now is complaining about something else or what. My question is, whose responsible if there is mold. Thanks!