WARNING! This post is written with the express intent to inform and entertain. Due to the differences in human nature, behavior and culture, it is possible that information contained within this post may annoy the reader although that is certainly not the intent of the author. Reading past this point constitutes an agreement by the reader to waive his legal right not to be annoyed by anonymous communication on the internet.
If you do not wish to waive this right, please stop reading at this point and use the ignore feature on this forum to avoid future posts by this author. Thank you.
Sounds like the result of someone putting in a spring kit to lighten the trigger.
The GP100 trigger needs to return fully before it can be pulled again. If someone's tampered with the trigger return spring so that the trigger doesn't return fully, the result would be exactly as you describe.
If the gun is new, it needs a trip back to Ruger. They'll fix it and ship it back for free. If there was a warranty issue, you can write them a letter when you get the gun back and reference the warranty repair, and Ruger will refund your initial shipping costs.