Oil leak

I have a small oil leak on my 99. It doesn’t leave puddles when parked but noticed it a few weeks ago. I let it sit for a few months then started driving it again that’s when I discovered it. I had my valve covers checked recently. I snapped a pic of what looks like could be the problem. Any help would be appreciated.

 

The oil cooler on side of engine and the hoses should be replaced if it's high mileage. I also replaced o ring on dipstick.

 

Thanks for the heads up. I just replaced the valve covers, half moons and cam plug seals. Waiting to see if that’s it or not.

 

Depending on how long it leaked it can ruin many bushings. I replaced all front to back. Last ones done today were panhard and traction bars.