I re-watched the episode a few days ago and... well... I feel the need to defend Buffy 🙂
In her dream, just a second after seeing Chloe crying she was attacked by the first Slayer and woke up with a start when she told her something. The scene lead the viewer (and Buffy) to believe that the message of the prophetic dream was in the first slayer's line and Chloe's crying just went unnoticed. At least to me, and supposedly to Buffy as well.
Of course in retrospect, one sees the scene differently but I don't feel Buffy is to blame. Also, what was she supposed to do? Any of the potential crying, out of fear or whatever, was predictable in their situation, but Buffy had already so much things to take care of. She didn't have the time to mother them IMO.