MONTE CARLO Purge Valve (gas tank to charcoal cannister)

[1988SS]

I had driven the car (1988 MCSS.....all stock) about 25 miles on a very hot day (~105 F). When I turned the car off....I could hear a faint noise coming from the engine compartment. I was able to trace it to the Purge Valve (gas tank to charcoal cannister). It was a kind of pulsating noise and could feel the vibration when I touched the valve. It continued for about 5 minutes and then stopped. Is this normal venting behavior or ?

Thanks for the help.....Darron