Snuzpod 4 question

[Nab28]

Hello, it’s my first time posting. I’m a FTM due in March. We’ve bought a SnuzPod4 and have recently assembled it. The mattress doesn’t seem to lie completely flat, and is slightly raised at the corners. I just wondered if anyone else had noticed this or whether I have assembled it wrong? Thanks in advance for any responses!

Mine does this because the mattress is so thin. The sheets put a little pressure on the corners and it curls up. Irritating but no issues when using it

Thanks so much @Brunilde that’s really helpful to know!

Yeh mine does it too much to my annoyance🙄