quote from terracoin-announce ml :
Subject: [Terracoin-announce] build 0.1.3-29 available
This update will bring back a shorter period used in difficulty
computation, until a better algorithm is implemented, making the network
resilient to the huge hashrate spikes we recently saw.
So this means that there is going to be another mandatory update sometime in the near future with yet another difficulty adjustment algorithm?
Yeah but there would have been another update when bitcoin gets updated anyway, so relax. Bitcoin isn't even 1.0 version yet. It's annoying, yes, no doubt, but it's a work in progress.