What would be the cause?

DETAILS???
1) Small leak of a few drops or more excessive?
2) Do you have a sunroof?
3) How long has it been leaking?
4) Have you been running the AC?
5) Any recent engine bay work done?
6) PICTURES?
7) Are the components guaranteed to never wear out? (Your car is 10 years old)

Thank you,
More details to come, but the dealership service department does an inspection when doing an oil change and has told us there's coolant around the oil cooler. I am mechanically inclined but always like to seek advice before starting a new job.
The leak is minimal like a few drops or residue.
No sunroof.
Has been showing signs of coolant residue for a few months but supposedly not a life or death situation but want to take care of it now.
Supposed to be a common problem on these motors and if so, hoping others who have repaired it personally can just give me a heads up before I begin..
Either the rubber seal on top of the cooler or the mounting gasket or a crack (what's more common?)
Haven't run the AC for a while.
Engine work, yes, I just changed the CVT Transmission.
Pictures to come if necessary
Components wear out?????
jk