Okay mommas questions cause I'm kind of worried. As a ftm I don't know but yesterday my doctor sent…

Okay mommas questions cause I'm kind of worried. As a ftm I don't know but yesterday my doctor sent me to the hospital because he was worried about baby anyways I got a call today asking for me to go back in today around 130-2pm for another nonstress test because " he wasn't happy with yesterdays results." Should I be worried? The hospital told me everything looked great and he was happy with what he seen and now he's not? Help!