Baptism perhaps, marriage no, as only the established church, Jews, and Quakers were authorised to conduct marriages in 1832. The fact that they had to marry in the parish church was the only way I have been able to even contemplate putting together some of my Southill baptist ancestors.
It always worries me when there is inconsistency; if they were siblings, why should Ann have been baptised and not James? Are there any other Carvers in censuses with a Wrestlingworth connection that you cannot account for, or is he the only one.
But the fact that the Carvers were serious Baptists, and Sophia was from Southill where the Carvers were from originally does make me wonder if it was a Baptist church related match, although again they baptised their children in the established church. He's not mentioned in Southill Baptist Church Book.
Have you been able to establish from Hitchin parish register if any of the Carvers were buried there? If for example John or Thomas were buried as children that would at least rule them out of the equation.
Regards
David