ok, i see that ...
// Check the version of the last 100 blocks to see if we need to upgrade:
static bool fWarned = false;
if (!IsInitialBlockDownload() && !fWarned)
{
int nUpgraded = 0;
const CBlockIndex* pindex = chainActive.Tip();
for (int i = 0; i < 100 && pindex != NULL; i++)
{
if (pindex->nVersion > CBlock::CURRENT_VERSION)
++nUpgraded;
pindex = pindex->pprev;
}
if (nUpgraded > 0)
LogPrintf("SetBestChain: %d of last 100 blocks above version %d\n", nUpgraded, (int)CBlock::CURRENT_VERSION);
if (nUpgraded > 100/2)
{
// strMiscWarning is read by GetWarnings(), called by Qt and the JSON-RPC code to warn the user:
strMiscWarning = _("Warning: This version is obsolete, upgrade required!");
CAlert::Notify(strMiscWarning, true);
fWarned = true;
so, it's a warning ...