Mine did that too. I lifted it up and sprayed a light coat of Krylon Crystal Clear on the table top, let it dry a couple of seconds, then dropped the mat down while it was still sticky. After making sure it was flattened out good with no bubbles I stacked several piles of books on top. Gave it a couple of days to dry and it's been fine ever since. Years now with no bubbles. It would probably be better to use some kind of spray adhesive, but I didn't have any so I experimented.