Yes, unfortuanately it is normal, especially with jerkbaits that have three trebles. I have hooked them just about everywhere, gills, eyes, belly, tail, everything. Sometimes it is because they slap at the bait and get hooked, sometimes they will be hooked with the back treble in the mouth and during the fight the other trebles will snag into the rest of the fishes body, occasionally ripping the back treble loose.