Are you poking it with your hook?
It depends on how you are using your middle finger when you crochet.
I will assume you use your extended index-finger for pulling the yarn tension and pass the yarn behind your first three fingers and then wrap around your pinky-finger. That is a guess based on how Amy holds her yarn in her knitting videos.
I use the thumb and middle finger of my left hand to hold the work near the bottom of the stitch to be worked. If you have a tight tension, you may be using your middle-finger to push the stitch over the hook. I use to do that; especially when I was using crochet thread and steel hooks for doilies.
Do you wrap the yarn around your pinky? If so you might try just a weave of the yarn between fingers without wrapping. Have it pass behind the first(index) and ring fingers but in front of the middle and pinky. That gives a looser tension.
If that isn't it, then tell us a bit more about how you hold your yarn, fingers, and hook as you crochet.
me us if I guessed correctly.
Master of Crochet, apprentice of Knit
OTN another Black & gold Diagonal Square Potholder
OTH Baby blanket
OTH Lace doily - A vintage pattern recreating from an heirloom.