That is incredibly bad luck - you must have missed it by a whisker.
I've noticed similar things happening many times. Maybe the 'Circle of Contact' (or whatever you want to call it) around the designated center of the flag isn't a true circle, but faceted - so it depends upon the angle your wheel sweeps past ( and it's own CoC would be the same), as to whether you get a contact or not. Also, often the center of the flag doesn't seem to be the center of the 'target'. The physics engine is pretty old and probably not very high resolution. Not having designed a level I don't know, just guessing.
Well folks I see that my Photobucket images are no longer working (this... with no warning.. after literally YEARS of using them as a host. And they pull the rug out from under their user base.
So I log into my account to see what all the fuss is about and to seriously consider upgrading their silly P500 program.
$399.99 PER YEAR!!!!!!!
Well Photobucket you can take a giant FLYIN LEAP.
So... anyway sorry bout all the lame images all over the forum board. Nothing I can do about it since we can't edit posts on BoD. And there ain't no way on this planet I am paying that much for any website on the entire internet.
You mark my words, folks... PB will go out of business if they don't reconsider.