it it normal to feel baby kick one day and not the next?

I'm close to 21 weeks pregnant (20 weeks 5 days) and yesterday baby was so active, it was actually the first time I felt her move so I was so happy and over joyed but today I only felt her inside inside (kicking bladder) and like once or twice but that's been it.
It it normal thats she isn't kicking around much today?