I stumbled upon “StumbleUpon”

Needless to say I am no native english speaker (nor writer!). In my previous post I used the expression “stumbled upon”. Since I had some doubts about the validity of the expression I googled it.
 
I learned three things:
  • There is a great social Web application called StumbleUpon
  • On the Web you can stumble upon everything (including StumbleUpon.com)
  • “to stumble upon” is a valid english expression