Yes it is. The rules are posted on the GSSF website. They say, "Everyone is allowed one “free reshoot” per stage." That is a re-shoot for one or all the strings depending on the stage. There is also re-shoots allowed for pistol malfunctions.
There is a few other rules competitors should be aware of. If carrying the pistol in a holster, "...the magazine must be out, the chamber must be empty and
the slide must be locked to the rear .". It is also a
lost brass match, which means no picking up brass, yours or others.
I volunteered to RO at the match both days. Never been to a GSSF match but I am a USPSA RO. I figured I better read the rules and found they are very beginner friendly. Start position does not require a holster and there is no movement.