strange routing behaviour

[eluser]plainas[/eluser]
This is rather strange, or at least there's something I am missing in here.

Here's the problem:
I enabled the querystring in a search form, problem is it only works if more than one parameter is passed, otherwise codeigniter sends a 404.
This is rather strange:

http://example.com/result/4ozi3o5g?q=bla&submit=submit <---- This works

http://example.com/result/4ozi3o5g?q=bla&a <---This works

http://example.com/result/4ozi3o5g?q=bla& <---This doesn't work

http://example.com/result/4ozi3o5g?q=bla <---This doesn't work

What am i missing in here?

[eluser]Yash[/eluser]
No idea may be kind of bug

Please report