There could be several reasons for your salinity to go up. Evaporation, salt not thoughly mixed with water when you added it. If you didn't net the new fish into the tank and dump the water they come in into your tank, the water they came could be higher, raising your salinity.
If you using a hydrometer to measure it could have air bubbles on the needle causing a false reading. What temp are you taking the reading at? Different temps could causes different readings.
I want to know what are you keeping at such a low salinity?
The jump isn't going to hurt you GSP. I would keep it there as your next step.
I let my GSP puffer tank salinity move around to mimic their natural habitat.
I keep my at 1.017 to 1.023. But they are older.