Its normal. Baby is still small enough and still has so much room that you won't feel every movement all the time. I didn't start feeling my daughter alllll the time until like almost 30 weeks but she's perfectly healthy and is the exact size she's supposed to be. Don't worry :)
It happened to ne when I was 27 weeks, I didn't feel my baby moving during the day or night. I was so worried but my husband told me everything was fine. I drank juice, cold water,no movement yet. I drank coke, nothing and took a warm bath. After an hour or so I started feeling this vibration in my pelvic area. Didn't go to the doctor. And found out my baby boy was lying in a different position than normal where I couldn't feel his movements. He changed his position at night and I started feeling his movements like normal.
As long as you have 10 movements a day it should be ok but if your worried check with your caregiver even just to ease your mind