With Wyvern 2.3, signature requests from our smart contract will include much more information. The request will be from Wyvern Exchange Contract - this is the expected behavior, and it is safe to sign.
For comparison, on Wyvern 2.2, the signature request is much shorter:
Troubleshooting Signature Requests
If you don't see the Sign button at first, don't be alarmed. In most cases, you will just need to scroll down in the wallet extension window until it appears. 
If you are unsure of a signature request, please contact us at contract.upgrade@opensea.io, or head to our Discord.