The gear which will be selected on a stop depends on your engine I think: the V8 will shift into the 3rd gear by default... If you switched to sport mode it will shift to the 2nd gear.
My experience - may be subjective: if you drive it sporty the time directly before a stop or the transmission "thinks" that you may need some more power it will shift to 2nd on a stop...

"Smaller" engine models will shift to the 2nd gear on a stop (at least this was the behavior on the e39).