It was planned. It will do MBJ tomorrow and LGW-SFB on Wednesday as well. Transition from Winter work (Scandi/Cruise flights) to Summer work (SFB, increased CUN and AUA) requires extra capacity around Easter.
Two based in MAN for short haul this Summer, one on standby and the fourth remains in Scandinavia. From next Winter they will be doing the bulk of the TUI Nordic work in the Winter.