Leaking Gearbox

[Camry owner]

Hi guys, 2 weeks ago I found few oil drops under the car. I decided not to bother due to the service that is going to be soon. However every morning the number of drops is getting higher and higher. Finally, I decided to check what the hell is going on. What I found is very high level of fluid in my auto gearbox. Last time fluid was replaced 40.000 km ago and I didn`t check fluid level since that. The questions is can this high level be a cause for gearbox leaking? Is it a typical problem? The reason for me asking is that it is clear that guys who do service to my car will be responsible for the leak (of course if high level can cause the leak). Thanks everyone.