you overdue a little bit here -- the USCIS will give them enough time and oportunity to proove them their marriage is bona fide. look @ me I am in a similar situation and underwent number of RFEs and two interviews so far, so I would not worry about being burned up front just because they married shortly after caming to the usa. as long as they are real married, it should not be a problem of approving, rather it will take definately more time (like my case 4 years). You guys just keep on collecting every receipt, picture, junk mail, put everything in joint name ASAP and you need lots of patients, and you should be fine.
Remember: you cannot prove fraud, where there is none