Water Pump Installation

I'm new to this forum. Tried doing a search but couldn't find a good match. My question deals with a 1999 Johnson 25 hp J25TELEEE. I removed and replaced the water pump assembly, following the instructions in the OMC water pump repair kit 393630, and SELOC manual. Removed gearcase but didn't drain gearcase oil. When I installed the pump and drive shaft assembly back into the gearcase felt pressure building in the gearcase as I lowered drive shaft in, Dah it's sealed. Cracked the top vent plug and everthing fell into place. After finishing stood back and was thinking, was I supposed to drain gear oil and is there any chance of drive shaft getting liquid locked into the pinion drive gear and not seating properly. Do I need to be concerned about anything else. Used all correct sealants and installed impeller correctley and drive shaft key ect. Any information would be greatly appreciated. Thank You for Your time

I appreciate your fast response and insite into my problem. I will check my gearbox for any water before I take it out, and will continue to monitor. I believe I might have to start asking questions after reading the manual but before I start the work. There is no substitute for expierience. Thank You again.