Rolex 8171 calendar question

[J..T]

Thank you oysterfisher for the welcome message and the reply.

I have owned this yg 8171 for over 25 years alongside a number of other triple calendar moonphase watches from other manufactures. (Omega and V&C).
My other simple calendar watches the month display needs to be adjusted at the end of the month no matter 30 or 31 days in the month. But my 8171 will automatically change the month display at the end of the 31 day cycle. (obviously its not a perpetual calendar to know which months are 30 or 31 days).
I just want to know if this is a normal function of the Rolex 8171?

Perhaps other 8171 owners can chime in regarding the month function.

Thanks again.