A diver made a rapid ascent but, later, wondered if it was necessary.
I was diving at a depth of 60 ffw (18 mfw) in 39°F (4°C) fresh water when my regulator began to free flow. I could not stop it so I retrieved my alternate second-stage and had trouble getting it in my mouth. I surfaced quickly and thawed the primary regulator; descended again to 25 ffw (8 mfw) and made a 3 minute safety stop. After the dive, I discussed this incident with a divemaster and realized that I should have left the primary in my mouth and ascended slowly.
A sudden free-flow can be alarming but breathing from a free-flowing regulator is a skill taught to open water divers and should not normally require a rapid ascent to the surface. It is important not to seal one's mouth around the mouthpiece of a free-flowing regulator in case the flow rate is greater than the exhaust valves can dump the excess gas. Fortunately this diver did not hold his breath during the ascent and was soon able to return to depth for a safety stop.