I think this must be related to the loss of FAA tax collection since it did not happen before. Currently it seems to me that when you use an ecert and click the "continue" icon under the fare given, there is always a fare change on the next screen. My observation is that it increases by 7% of the ecert value one is using, e.g. if you are using a $350 ecert, the fare will be about $24 higher. I hope this problem can be noticed and solved by UA soon.