When a question is migrated, at least from a main site to a meta site, the "new contributor" label is not shown below the user card.
Here is an example from Ask Ubuntu Meta
Also one from Stack Overflow Meta
In both cases the accounts are less than a week old and have only 1 rep, so should get the label.
I thought this was specific to Ask Ubuntu at first but it seems that it possibly would effect every site.
Due to the criteria for the label to show, examples are a bit hard to come by but I will add them as I find them.