True, although there is always the possibility that she was someone who had been married and widowed since the previous census, so that this name would not have appeared earlier.
I'm wondering if anyone knows if there would be any parish records to back up the IGI. It says they are extracted, but it doesn't say from where, not even the name of the parish, which seems odd to me. I'm thinking that if there are births, perhaps there are marriages somewhere, so that I could track the parents. I'm also wondering if there were any other siblings, although none are obvious to me on the IGI.
I have another woman in my tree who married at about 50 for the first time, was widowed, and then lived to be 100!