Yeah it's normal,it's just not noticeable during the day,and at night you still have to be more or less directly behind it to see it. It's real obvious on the CFM 56's. When we still had F28's,I remember at night you could see the lightoff at engine start and watch the flame propagate from the two igniter equipped burner cans and spread circumfrentially around the engine to the other cans. Since the Spey had about as much thrust as horse passing wind (
),you could still be fairly close to the rear at lightoff without becoming tumbleweed. You could also hear the flame as it propagates as a series of short rumbles. The Tay's do this too. Ya gotta love it.