that'd be my guess (it happens to all of us at one time or another). To do lifters to the nth degree (which I do now after my recent lifter fiascoes!) is take em apart & clean thoroughly then reassemble dry then install em & set preload individually if I have adjustable rockers & if not then I before hand on mockup individually checked preload (it should be about the same on all of em but cant assume anything for everything being the same length/dimention) then get #1 cyl to 15 BTDC compression then preoil. I also toss the flimsy clips & use hardware store 11/16 internal snap rings in their place & a guy said to have the sharp edge side down which I thought was backwards but I am going with what he said. It might be better to lightly lube internals with WD40 as opposed to dry & I am open to changeing that but that is where I am at now. Holler how it turns out