@bpydzinski - You framed it right do we have any answers here. Its been happnening to my site as well. The site is opening up in Operamini on all versions and its an XHTML build it renders perfectly fine. But it does not record the impression in Google Analytics. Is it a flaw in Opera Mini?
My largest traffic comes from Opera mini and to see a huge drop in the number that is not tracked is not helping my business.
If some one from the OPERA team can help answer @darshwill question I think I will too have an answer.