What should an engine sound like?
I think that everyone is hesitant to assure you that there's nothing wrong. No one wants to have said it's OK and then find out that you dropped a valve or something like that later. I seriously thought it might have been a bit noisy but not to the point that I'd be panicking. But I've known guys that were amazing at picking up on problem noises that I couldn't. An inspection of your oil and a look under those valve covers would give you more re-assurance.
If you've got a stethoscope (or at least a 3 foot length of garden hose) you could listen more closely along the lengths of each valve cover. I would think that the sound should be pretty consistent all around and if you were to find a spot that was a lot noisier then maybe have more reason for concern.