Yes, it's strange that nobody haven't noticed that.
And you are right about the missing comma in the sentence from the lesson about the "Briefträger". I've corrected it. In general Irene is very attentive when she creates lessons but it can happen to all of us that we miss something or that the lesson included regional adpects of the German language. For example I've noticed that Irene used "Haustüre" instead of "Haustür". There is an article about this here: http://www.spiegel.de/kultur/zwiebelfisch/0,151...
(but it is probably to hard for you to understand it). It Standard German it is "Tür" not "Türe". I've added a note to the lesson to clarify this for all further learners.
Please continue to ask if you find strange things :-) All the German speaking members love to help.