A power steering system consists of a reservoir, feed hose to pump, pressure hose to steering gear and a return hose to reservoir. It is possible that the air in the system caused the system to burp which could push fluid through the vent in the cap or over the sides of the reservoir if the cap is off but I have never seen an over flow hose on the reservoir. As for your growling, it is not uncommon if you foam the fluid. If the vehicle sits for 24-48 hours the trapped air usually migrates to the reservoir and out to the atmosphere.
Randy