It looks like a flaps 1 or 2 take off or something like that. I do not know about the B737 NG but I do know about the A319/A320.
It definitely had loss of lift at rotation but then it was a good idea to let it be a longer time on the RWY to gain more speed.
Pitch trim is another possibility but then you would see the horizontal stabilizer pointing down or up depending on what pitch trim is set.