Case 580b hydraulic filter change.

Hi all, before completing the repacking of the loader cylinders, I replaced the hydraulic filter. In taking the old filter out, I noticed the "hole" in the filter was facing down, so I put the new filter in the same way! I just dropped the new filter in, poured in some hydraulic fluid and screwed the housing back onto the filter head. After completing the packing job, I poured in about 2 gallons of hydraulic fluid until it ran out of the lower hole below the fill hole. Loader worked and responded well, but I got to worrying about the hydraulic filter I replaced. I am new to all of this (as you can tell ) and I read somewhere on this site that the filter should be attached to the filter head before screwing the housing on! I hope I don't have to take the filter housing off again, then it would be a mess! Hopefully some of you can give me some insight on this. Thanks and take care...