desk build, surprising wood movement/crack.. or something else?

[ianab]

The heat might have accelerated the failure, but the underlying problem seems to have been that the wood held too much moisture, which the heat removed.

Nevertheless the bond was insufficient and might have been improved by the use of better glue, such as WEST epoxy. Also I use many biscuits (WEST epoxy glued) in a joint like that.

In this case though it wasn't even seasonal or final drying that caused it.  It was like the middle area of the table (under the laptop) was moved to the Sahara Desert in the middle of summer, and the rest of the table stayed in the room. So the drying and movement was uneven. Better glue might have held, but at some point the stress can build so much that the wood itself cracks. 

The air coming out of a computer's cooling vents is not only warmer, it's at a lower RH because it's the same air that went in, just warmer.

[Gary G™]

When you built the table top, was it a sprung joint?
If so, how much?

[mound]

When you built the table top, was it a sprung joint?
If so, how much?

No.. I always think about trying that technique, but have never done so.  The edges were jointed by hand though, but square and true across the length.