Would this trigger a P0442 code?

[Redog]

I know what the code is, so we don't need to go there.

Gas cap is fine, no broken lines under the hood. Felt the one around the master cylinder and it didn't feel cracked or broken, so I look at the gas cap again.

When I took it off I noticed that the little metal (tin) flap was stuck open. I just gased up and it was closed and no P0442 code was present, two days after I fill up (about 7 miles) the SES comes on and this flap is open.

I'm going to see if I can replace it anyway, need a few small odds and ends for the Alero that I can pick up at the junkyard