@giorginho are you sure about this? I thought the answer was Yes in the first case (extra award miles roll over from Silver to Gold) but No in the second case (once you qualified for Gold your award miles are zeroed). In fact, this is exactly what I experienced earlier this year. My current statement claims that I need 12,000 tier miles to maintain my Gold status, even though I collected more than 24,000 tier miles since I became Silver.

Shuly