Suspect by who? Exactly? In detail.
And really, if you're talking about people in the McCain campaign who actually knew Palin and could dish (real or invented) dirt, wouldn't it be more likely that they were long-time McCain loyalists, rather than Romneyites who somehow happened to get picked up along the way by the campaign?
That was in 2008-9 when that story that was picked up by the American Spectator and believed so many people came out. A year or two later, when campaign advisors were gearing up for 2012, you did find Romney people talking down Palin, in the way that people in one campaign do put down prospective rivals, but that story that secret Romneyites in the McCain campaign were sabotaging Palin to clear the way for Romney back in 2008 was a questionable one.
That said, it does look like Kevin Madden, who had worked for Romney in 2008, was putting Palin down in interviews before the election. My point, though, is that there was enough bad blood between Palin and McCain's people and enough incentive on their part to blame her for their defeat that you don't have to put the blame for whispers or rumors at Romney's door.