@noahkuhn, what version of ACF are you using?
I posted in the bug report topic posted by @drunkrocketeer http://support.advancedcustomfields.com/forums/topic/acf-returning-id-as-string-instead-of-an-array/. I am not seeing this on my test site with 5.3.2.2 (latest version). But I have not tested with ACF4.