Or if the split lasted long enough (more than 100 blocks), transactions that involve generated coins on the shorter chain would be invalid at the merge.
Interesting info, so other than some double-spending issues, as long as the block chain isn't separated for more than 100 or so blocks (or 16+ hours), If there a hard coded limit on split delay? Meaning if I had a small network split from the public network, spent some coin around, came back a few days later and got them sync up to the public network (other than coin generation if it happened) transactions should be fine?
There's no time limit. Assuming you weren't spending coins generated in the minority fork, or spending someone's double-spends you received, your transactions can get into the other chain at any time later.