Oil leaking around engine cover

[brian.white66]

I'm new to boating, so excuse the ignorance but I have a 1982 Johnson 70hp on my boat, I noticed this past weekend that some oil had leaked out around the seal on the cover for the motor, I haven't pulled the cover off really just because I would'nt know what I was looking at anyway, motor ran fine though all day, is this something I should be concerned about or what should I look for when removing the cover.