Well, if you asked me, I'd say yes, this is common as of late. My last 2 orders have been like that. Most people swear by Ritek....I just swear at Ritek...
I use 4gb as a rounded size....I have had some disks with issues at 3.8gb or so as well.
My take on it is balancing...there must be excessive wobble that causes the outside of the disk to be unreadable (or unwritable). The die formula is still one of the best out there....it's just this issue that I have had lately. This would be consistent with your leadout issue.
Have you tried any other media on your drive?
I hate to blame the media....but, being an owner of a Pioneer, it's about the only thing I've ever had problems with.
Here are some obvious (and cheap) things to check:
DMA enabled? defragged harddrive lately?
Here's what I'd do (and did)...
Buy a 10 pack of high quality jewel case media (Maxell 4x, made in Japan, MXL is probably the cheapest of the high quality). Try those. If the issue still exists...I would tend to blame Nero, burner, configuration, etc. etc.
Good luck my flabbergasted, fugged-up friend