No, I have found that for some reason, only Pitt's are questioned. Nobody questions Notre Dame's either.
Alabama's are questioned....almost entirely by Auburn blog sites.
In fact some schools, like Texas A&M, have recently added to their claims based on the NCAA records book.
Pitt has been consistent with its claims at least since 1970, because it has consistently relied on that
SI compilation of all-time national championships dating to 1967. Pitt has not deviated or added to these claims, with the exception of the unanimous 1976 national championship.
However, Pitt has one title in its list of claims that could very much be questioned: the shared title of 1934. This one appeared in the SI compilation and is credited to Parke Davis' selection. Davis was the most noted football historian of his day and the editor of the annual
Spaulding's Football Guide... which was the most noted football publication of the era. The problem is that Davis died before the 1934 season, although the 1935 national champion (which Pitt shared) was picked for the 1935 Spaulding's Football Guide using his byline (as it was thereafter after until 1937). The NCAA's Official Records' Book only recognizes Parke Davis selections actually made by him (e.g. through the 1933 season). However, the SI study, and Pitt's claims, predate the NCAA's compilation of championships in its records book. Additionally, the 1934 season's most of recognized champion, Minnesota, actually beat Pitt in Pitt Stadium that season. So 1934 is very questionable, although the rest of claimed 8 have strong historical legitimacy (as much as these things can).
Does that mean Pitt has only 8 legitimate national championships? Well, no, the 1910 undefeated and unscored upon team is recognized as a national champion by almost every compiler of such championships, including the NCAA records book. Pitt has never claimed 1910, because it has only ever relied on the SI study. So, just swap 1910 for 1934 and you are back to 9 (and this is exactly how
College Football Data Warehouse lists the 9 national championships that it recognizes for Pitt). Of course, these 10 seasons (including 1934 & 1910) do not account for the SEVEN additional unclaimed years that Pitt has been named as a national champion by other independent, third-party selectors of national championships (of those 7 years, 1980 and 1981 are also listed in the NCAA records book for a total of 11 listed Pitt seasons).
And don't tell the WWII veteran who can recount watching Marshall Goldberg's exploits while at school, and who continues to sits in from of me at almost every Pitt home game, that these pre-war titles are not legitimate.