why does this always come up before installing app on cydia?

Me too.

And a few weeks ago, it was another signature. And two month ago, a third. I guess it is an error in a repository, Cydia decides that something is not right and ignores the affected files, just to be safe. After a while, somebody with the ability to fix it does so. Until then, annoying but probably harmless.

 

Have you tried the apt-get update command in terminal? Usually works for me

 

This is just a error when the http request failed, usually due to server down or just a lot of traffic (like the first couple of weeks when a new tool is released), nothing to worry about

 

off peak

Just means there are alot of people pounding out the servers. Should go away on off peak times.......

 

Clear your q and try again