Games : Random blocks missing underground - 1.8.1

Note: I'm not sure if this is server-specific or not. Also, this is unrelated to do with the missing-blocks issue about known blocks (as in one of my own structures) going missing

I have been diamond chunk-mining at level 9 (then 6, then 12, if not found). I have noticed very frequently that sometimes a block is just missing. Sometimes it appears to have a thin moving-lava, but that dissapears immediately.

Also, I just recently started finding a dozen or so blocks missing in a "vein" looking pattern down to the bedrock. And... the bedrock/area is completely lit up. No lava or Torches.

Those might be seperate issues or related, not sure. On a possibly unrelated note: I have mined a number of full chunks (not a single block left) that did NOT have Lava, nor had a cave running through them, and didn't find a single Diamond. That's just a bonus, but might be related if random the missing blocks are where Diamonds used to be.

The server has no mods or texture packs. This information has not be altered, it has always been 1.8.1, and has never had mods or texture packs.

@ColorFusion - incorrect, every single chunk is created with a single diamond vein. Sometimes part or all of a vein is overwritten by a generated structure (such as cave/tunnel/mineshaft/lava), but the diamond vein was there before the structure generated. Also sometimes, the diamond vein belonging to the chunk happens to become offset into the neighbor chunk, meaning the neighbor technically has 2 veins and the original chunk has 0 (though one actually BELONGS to the original). But that is rare, and if that is the case, I'd find 2 veins in a neighbor.

So back to my question: It is new to me that random blocks or "Veins" or blocks are just randomly missing. I haven't played 1.8.1 a lot until recently (my last real playing was on 1.7.x), so this is new to me, and I wonder if it is a glitch that is deleting diamonds or what.