I wouldn't think that'd be a huge deal...in the wild they don't really get fed on a schedule, and both my girls are fed on a staggered schedule sometimes and Roo's never taken badly to it. She's usually just a more aggressive feeder on days that fall later than usual on her feeding time. Maybe yours is just picky? ;)
Maybe she's just not feeling well, or preparing to go into a shed and just a little grumpy. Maybe she's been handled too much, or something from the last meal upset her tummy or took longer to digest...could be any number of things.
I'd try scenting with a gerbil or, if things get really drastic, feeding a f/t gerbil (or maybe a baby dwarf ham, since she's so small). I've found that generally picks Roo right back up out of her slump.
Good luck!