Which one, i dont see any huge walls? Or you mean the 2.5btc one?
Its more then ok to me, as long as people think its worth buying at these prices, sell walls will only be a good thing... else what do you think will happen if it gets pumped up...it will go down fast...so if it goes natural then its ok by me. There will always be people selling although i agree i dont know why anyone would sell at this point in time.
No no premine at all...but some bought in at 1000/2000 sats or some even earlier...so those are probably taken profits the last few weeks. Shouldnt be a lot of sellers left as the top 10 richlist are longterm holders or the devs who bought in with their own money.