90% of water damage people do exactly what you're doing. Shake the water off, let it "dry" over night, and test it the next day. It works! So you continue to use it.
All the while electrolysis is at work, chewing away the guts of your phone, and you don't suspect anything until its too late. By the time the motor starts buzzing, the speaker cuts out, or it bricks - the damage is permanent.
Heed the advice of others to leave it OFF and put it somewhere warm and dry - to get the moisture out before it can resume chewing up the innards.
Just perform a search here and enjoy the hundreds of threads covering this subject.