HELP... leaking toilet supply line

I needed to remove a toilet today... Unfortunately the shutoff was corroded so I shut off the main water supply in the house.
An hour has passed since then, and the toilet has been removed. Now, the supply line is leaking. Once every minute or so, it gurgles and releases about 1/8 to 1/4 cup of warm / hot water. This is worrying me because I assumed the supply line is normally cold water.
What could be causing this? The flow is increasing gradually in both volume and frequency.
Help please!
Thanks.
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Dev wrote:

It could be that the water heater is firing (heating up) and causing the water to expand.
Open a tap at some level below the toilet. An outside hose tap or even the drain cock on the water heater (shut off the heater).
Jim
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Then call 911 and yell HELP as loud a you can :)
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