Hi girls. I had that too - really active days and then almost nothing. Like Alan said, it can just be that your bubs is having a long rest. My OB also said that sometimes after bubby has gone through a bit of a growth spurt they're quiet for a while- I usually found bub's quiet days coincided with days where I felt really cr*p - she'd gone through a growth spurt and it had drained us both.

Definitely worth checking though to get some reassurance - I had a few melt downs when I couldn't feel Ed for a few hours at a time!