I think cranking the bottle real tight will get the seal fixed. That or normal ware from putting the cap on will break in the threads to eventually seal good.
I hope this helps. I filled the bottle with hot water and then submerged the bottle in a pan of hot water. With the bottle in the hot water I folded the tube over and did the squeeze several times. Before I did this I had a little seep but after this I didn't. It worked for me but who knows if it was the process or just the normal ware you spoke of.