Just wanted to update the thread -- after reading a few forum threads and the articles about voltages, I decided to try switching my VSUS from high to low in the service menu. In addition, I tried some different calibration settings (the previous had contrast at 96, these at 81). Nothing else was changed and I watched the Stanley Cup Playoffs last night (Go Blackhawks!) where the yellow blobs were most noticable on prior viewings.
Not sure if it was the calibration settings or the VSUS change, but the blobs were greatly diminished -- to the point where if I didn't know they had been there before, I wouldn't have ever noticed them. To me, hockey is where I'll notice it the most, so overall I'd say this fix worked for me. I'll be sure to watch the next game on Saturday night with the same settings to see if I get the same results (fingers crossed). I couldn't see the blobs during commericals where I had normally seen them either -- on light grey or blue colored backgrounds.
Perhaps others with the same issue should try the VSUS switch to see if they notice any improvement. I'm still going to have a tech come look at the panel to see what they say -- it's obviously defective -- but at least not all hope is lost if Panasonic won't do anything.