Essentially yes, it's saying that you got a big message.
Since a 68MB data item is highly unlikely, there was probably some breakage in the datastream.
The protocol for splunk->splunk forwarding includes a length indicator number, which causes the receiving code to allocate memory. To avoid breaking the receiving Splunk, it does not blindly trust the size, but for cases of very large length numbers logs the problem and does not allocate the memory.
This could be a case where the forwarder is encountering some kind of memory corruption bug, where something is communicating to a splunktcp:// socket which is not quite conformant (hard to imagine, but possible), or when the stream of bytes in the tcp socket is getting messed up via some other means.
We had a known problem with early versions of 4.0.x and late versions of 3.4.x where the forwarder would sometimes inject 'heartbeat' pseudo-messages in the middle of other messages, corrupting the datastream. You may want to evaluate if tchuxxx.xxxx.com may be running an older version of splunk.
