Departure was delayed by half hour.The spokeswoman VP couldnt account for why it did when interrogated by a journalist.
According to FR24, the inbound DUS-BCN flight touched down a couple of minutes after the 07:55 STA, so was probably 5-10 minutes behind schedule by the time it arrived on stand.
With a 40 minute scheduled turnround, that wouldn't be enough to account for a half hour departure delay, so there may have been a technical issue.