It is difficult to point to an exact reason for this change in sentiment towards the Dollar right now given the fact that the US economy is in better shape than Europe and Japan ( that is not saying much) and appears to have entered a season of rising interest rates accompanied thus far by a soaring stock market. For the first half of the year that was all that investors needed to see and into anything US Dollar related they ran. Something has changed that - or at least it so seems.
It might well be that the US fiscal house disorder is coming back to the forefront of investors'/traders' minds once again as the federal government is up against its borrowing limit and once again the usual circus in Washington on the Potomac is back in town. Whatever the cause, the Dollar has now moved lower in 4 out of the last 6 weeks and in the two weeks that it did manage to close higher, the high of that week did not exceed the previous week's high price. That is not exactly a show of confidence as it is certainly not bullish.
While it is still higher on the year (barely) the chart is picking up some signs of waning upside momentum. The high price made this year in July exceeded the high of the previous July 2012 and that outside reversal pattern but the indicator did not score a fresh high; instead it registered a lower high resulting in a BEARISH DIVERGENCE. This in and of itself is NOT A SURE Sell signal unless it is confirmed by subsequent price action, which of course the market did. Even at that, the Dollar has not broken down technically on the price chart .
I would have to see a weekly close BELOW the band of "MAJOR" support noted on the chart to turn bearish the Dollar. Right now I am ambivalent towards it, being neither bullish or bearish except for the shortest of term trades.