4-Piece Bamboo Sheet Set (Sale)

I just put my new sheets on my bed last night and they are super soft I love the feel, but I was surprised at the fit. I have a king-sized mattress, and have never had a problem with sheets fitting, the bottom barely fits, and it has some odd stitching at each corner - possibly to help them stay on a mattress that doesn't fit so well? I'm not sure, but they were hard to put and keep on, then the flat sheet, well it's so short on the sides it can't be tucked in on either side, which made me wonder if they sent me the wrong size! I checked my receipt and it says king. I had already thrown away and recycled the packaging so I can't check for sure. But I doubt a queen-sized bottom sheet would fit on a king. so bottom line, I love the soft texture, it's heavenly, but it's runs small. Two people in a king (which is logical), I suspect that it won't cover both people with the sides so short.