Hi All
Our ancestors had to pay for Baptisms/Marriages/and Burials just like we have to today except it was to the Church.
Therefore I suppose if times where hard children may not have been Baptised at the time of birth so it is always a good idea to see if there is a later Baptism (i.e. before a marriage).
Looking through the registers of olden times it shows when the Vicar/Curate etc used to go around his Parish and round up all the families that had not Baptised their flock at the Parish Church and get what we call a job lot done all at once.

lol.
Other than that I agree that the Vicar may just have forgotten to note.
Cheers Sandy