Unfortunately there are hams who don't necessarily recognize that freqs like 145.8 are reserved for use (granted, by convention, not necessarily by some sort of legal rule) by others (and decide to use the freq anyway), and there are those that like to 'pretend' they're something they are not. Every hobby has its share of bad apples, sad to say.
However, it is possible they might use the old 143 mhz freq for talking to the ground controllers in Russia - I don't remember what the old freq was, but I'm sure someone can post it. It has been reported, albeit rarely, before...
You have to have some idea of what the crew schedules really are to judge whether you are really hearing the ISS or not. It's certainly possible that they could fire up 145.8 at some point, but it's hard to predict. And with the next Shuttle mission, they're going to have a full plate for work, for sure.
The schedule rdale put up shows the crew's sleep time is 2130-0600 UT, so here on the East Coast, if you hear something on 145.8 during that time, it's unlikely to be the station. I don't think the repeater mode on the Kenwood has been reinstated, at least I hadn't heard of it as yet.
73s Mike
[edit] Come to think of it, didn't I read somewhere that a bunch of hams were trying to use the station itself to reflect signals? If so, at least some of the traffic on 145.8 might be involved in this.