No, unfortunately I didn't capture the message, it said that legacy addresses will no longer be used, and you should only deposit to P2SH addresses. Deposits to old addresses were going to charge an additional fees.
As you say at the end, I also think that it was something temporary and they turned it back.
I have not received a response from either support or TheQuin.
I hope they fix it and that address is still assigned to my account.
Now that I am looking at your previous screenshot again, it does look like this message was displaying on your account. It is partially blocked by the DEPOSIT BITCOINS pop-up but inside the third yellow notification box there is a message that has to do with addresses.

Hopefully they will go back and credit these deposits, but maybe they are waiting until the address changes are officially implemented.