My Mom just saw a health segment on the news about night terrors -- and it seems like maybe that's why Maddie is crying in her sleep. Night terrors don't always happen at night but do happen in infants when they get caught between deep and REM sleep. Since 3-month olds are just beginning deep sleep it seems a likely time for terrors to happen.
I also learned that terrors can be caused by lack of sleep. I've been recently reading about how infants need 15+ hours of sleep each day, but most only get 12. While previously Maddie was sleeping quite well and routinely, lately she just hasn't been. Her napping during the day has been more sporadic and I think maybe she gets thrown off schedule when we run errands or such. So maybe going to the cottage this weekend just knocked her off track. Alas, we're done with the cottage for the season anyway -- so maybe we'll stay close to home and sleep a bit.
Oh, and it turns out that infants can even have nightmares about feeling hungry. That sounds pretty much like Maddie!