Greetings all. Thanks for any help.

I've got a 1989 3.0l Monty and I just finished my first head removal and install. No applause necessary. I had the heads rebuilt by a highly recommended shop and they looked really nice. I finally got it all back together, it started right up (no-one more surprised than me) BUT, there is an oil leak where the passenger side camshaft emerges from under the camshaft cover. I would like to assume that the shop installed the seals correctly. Is there something about how I re-installed the rockers that could cause this? I will accept any answer that does not involve having to tear down the front of the engine again.