i've had it a handful of times, always before or after a lucid dream
the first time i had it it was during a weird nightmare where the girl from the ring was crawling up my lying body to come face to face with me, i couldnt move and it was terrifying because my eyes were open and could move around but my body was stuck
other times its just been a somewhat uncomfortable but not overly bad experience
nothing to worry about honestly, once you've felt it one time and know what it is its no longer a problem