Normal? No. The liner should be wrinkle free for the entire useful life of the liner. Wrinkles indicate a problem. The most likely causes of wrinkles are: 1. The liner was poorly installed. 2. Excess ground water has shifted the liner. 3. Low water PH has expanded the liner. It's OK to live with the wrinkles as long as they aren't causing a problem with vacuuming or other pool maintenance. More importantly, the cause of the wrinkles should be addressed. Call us for a sump pit install or ground water control system. If the wrinkles are causing maintenance issues or you just can't stand the sight of them, most of the time this means a liner replacement.