Is a 3-month Z-visa valid?

Hello! I have been in China for more than three years now as an ESL Teacher. For the past three years, I worked in one of the schools somewhere in the northeastern part of the country and was given a Z-visa with a one-year validity. Now, I transferred to another workplace somewhere in the southeastern part of China and applied for another Z-visa. However, the PSB only gave me a residence permit that is valid for three months. Do I have to worry about it or I just need to come back to the PSB before the said visa expires? The PSB Officer told me that it can be renewed, though, before 90 days. Thank you!