I've had it happen. People claim it's a bug that has surfaced periodically as Bungie attempts to either fix or nerf fusion rifles. I've heard people say that it's triggered by dying while firing while others have said that it's simply related to lag.
Most people agree that dying/unequipping and then equipping will usually fix it.
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Ah glad it is actually a thing. Thought I was going crazy. What I do know is it : Definitely is not triggered while dying, as it happened while I was on a streak. Definitely does fix the problem when you die / re spawn.