I think so. It's a new form and Gajeel kinda foreshadows it when he says he's the last one to get a DF.
Yea, the flashbacks were what made me think this might be a Dragon Force
Also, I know he has scales like a dragon when he goes into the iron scales thing but, his DF resembles that of Natsu and Sting/Rogue heavily
Yea, that was the major source of confusion for me. Cause he get scales when he uses iron skin as well. Them not stating explicitly that it was a DF, was a source of confusion as well. Since, during DF of all other characters, especially when they use it for the first time, they explicitly mention that it's dragon force.
But maybe Mashima stopped saying it too, he didn't mention it when Natsu activated DF against Zeref, Merc and Aldo as well, right? Let me check, not really sure about it.
Edit: it was mentioned against Zeref, by Mavis. But nobody mentioned anything vs Merc and Aldoron
But now, upon looking closer at the panel posted, the scales on his face indeed do look like the scales that Natsu shows while he's on dragon force. The scales that slowly retreat after powering down, seems very similar to how Natsu uses DF
I guess it's kinda confirmed then, it is dragon force.