Exporting adds a small delay???

Hello everybody,

I am in the midst of heavy exporting to meet a dealine and wanted to check with a nulltest to see if the final mix only differs in form of the corrections.
However it seems as if on an export Nuendo has added a very very slight shift / delay. A few samples (maybe just one?).

Is there a known bug? Nuendo 4, latest, Win7.

Cheers for any help, too little time to really hunt this down right now.