The answer is no.
Why does it matter?
Well the tombstone of Rebecca Mullin, discussed in a previous post, indicates she died on 29 February 1849. That date did not exist in 1849.
The question remains: "When did she die?" Now that I know the date is incorrect, I'm really curious about her age. In the grand scheme of things, the spelling of her name is a minor issue.
The tombstone would be considered a original source for her date of death and would contain primary information--assuming it was carved relatively close to when she died. But because the date is clearly incorrect, it raises a slight shadow over the accuracy of other information contained on the stone.