New DE server is still a virgin though.

And the cherry has been popped! It was a de block.

How can you tell if it is a DE block?

Well I can see the consoles so I can tell from there, but if you look at the blocktrail link above and follow the transaction details with this link:

https://www.blocktrail.com/BTC/tx/bb5a1eba080061becfe1e07d6e954bfc9f695391f68a8e5437b08b59ee1f6b02#tx_messages

Look at the bottom where it says "DECODED OP_RETURN AND COINBASE MESSAGES"

I have a unique signature for de that should be obvious there.

Im assuming you mean this

ckpool/de/solo.ckpool.org/

Thanks