Second guess

http://britishexpats.com/forum/citizenship-passports-spouse-family-visas-uk-196/uk-family-visit-visa-decision-made-2-days-873481/

"(Original Poster): .............. I heard the visa processing time takes around 10-15 days but on 25th, I received an email from the gov.uk and they said a decision has been made. It also had my application's reference number and it said a decision has been made on my application and my completed application has been sent to the VFS centre.

The next day I received an email from VFS which said they have received my passport and documents. I had opted for passport collection in person (unfortunately I am out of station ) and can't pick up my passport until 5th March.

I am extremely worried because I read on a few forums saying if the application was processed quickly, it definitely means rejection. This is the first time I have applied for a UK visa.
Is this true? Does this mean a refusal??

Comment: No way of knowing until you collect your passport. No point trying to second guess it."

I wonder what is difference between by using "guess" and "second guess" in that case.