I also had an interview with a PI at U Mich in mid January, and have not heard back. I applied to UCLA (CS Ph.D) and have not heard anything. According to UCLA's website, they will send out Ph.D results in "late February".
"Q3. When will I be informed of my admission status?
A3. If you are a Ph.D. applicant, you will receive an email notification concerning your admission status by late February. If offered admission, you must accept or decline our offer no later than April 15. M.S. applicants will be notified by late March and must also respond by April 15."
Taken from here
Good luck everyone!