Could be any number of things. The Dash 8 has a few landing gear issues, resolved by now, but a little extra care is not surprising.
The main gear suffered locking issues, perhaps the pilot was using the greater forward airspeed to lock the gear. Also it takes quite some time for the gear to extend fully on a Dash8/Q400 (I could be thinking of an ATR though, not entirely sure).
Was it busy around the field? ATC may have given a speed restriction for sequencing or somesuch. Hard to know. Change in active runway could also mess up a pattern. (EDIT - for this section jsut read GR's post
)