. The pressure from the oil is only just enough to remove whatever clearance there is inthe valve train, but not enough to actually open the hydraulic valve itself
http://www.sbintl.com/tech_library/a...fters_work.pdf
In other words, with the right lifters without oil they might click a little until oil fills them and pressure builds, a few seconds.
If the valves are good and the gears aligned than tightening the cam bolts should not have cause a leak.

On the head bolts, how do you know? I have replaced them with new every time I change a head but looking at the bolts after torquing them they have marks, they are stretched so how do you know? Does the second mechanic have a Ouija board? In fact how do you know the head bolts are new from the vendor? Off ebay chances are they are from China and who knows no days?