6-71 Blower Question

Hello. New member here. I have just purchased a 55 Chevy street rod with a Littlefield 6-71 blower. I know absolutely NOTHING about a blower! I drove it only once to a cruise-in and now I have gear lube all over my fenderwell where it appears to have been blown out of the bottom gasket of the front cover. I see a small pressure relief valve on the front of the front cover. It has a small button in the middle that can be pressed - obviously to relieve the pressure. My question is: Am I supposed to press this each time that I turn the engine off to relieve the pressure? Or is it supposed to do it automatically, and I really have another problem?
Thanks in advance for your knowledgeable help, my new friends!
Johnny in B'ham