Legal Question in Real Estate Law in California

Rather peculiar, especially if the three-day notice is in regard to nonpayment of rent. My questions to you would be (a) whether you have received any previous notices, and (b) whether you have proof of payment (or can get it) such as a paid check copy. If you are mailing your payments, maybe this one is lost or delayed in the mail. Next, do you have a clear channel of communication with the owner, landlord or manager? If so, inquire in person. As a last resort, make another payment, in person if possible, clearly indicating on your check that it is a second payment replacing one apparently lost in transit. There may be other problems and/or solutions here, but based on the facts given this seems like the most useful advice.