I don't think now is a good time to lock in the rate as it seems to be on the decline after overshooting the prices for the past 2 years. It used to be a smart choice to lock in the rate (back in 2000 when rate was at $0.17, it doubled within 5 years). Because of the housing boom and global energy crisis, the suppliers raised the energy rates annually over the past years, but since Enbridge started readjusting the rates for summer and winter periods, it is not hard to see that it's not justifiable to commit to a 5 year plan for the time being.
My advice is to sit and watch.. the trend changes all the time. Good luck.