Maybe.... or not. According to Open Secrets, McCain has received $11,750 from Freddie Mac, (vice Obama's $18,400).
They don't give an amount for Fannie Mae contributions, though to miss being on the list, McCain's amount would have to be less than $16,000 or so.... And Obama was evidently given about $88,000.
Obama is vulnerable on this, but the fact that McCain benefited from any contributions at all would probably dampen the media impact of the issue.