John
I have ad this problem before with lounge carpets and they have all gone back down taught after a short whle. A lounge carpet is obviously a lot bigger than a bedroom so has a larger area to stretch.
When i did one of my first carpets, it bubbled and i said to the customer about it. She said it's okay, it happens when i clean a patch, and it's the latex. She knew because she worked in a carpet factory making them.
I believe it's called reflex relaxaton. Use the search to find other postings on this.
Dave