Grin's network hashrate almost doubles overnight

[Swizz_beatz]

Guys, I don't know much when it comes to mining but Grin's network hashrate basically doubled overnight. Apparently the difficulty doubled according to someone on the forums which has made it less profitable. 4 possible explanations where given since no drop in hashrate was seen in other coins. One of them is someone got 100K plus GPU miners on within a short space of time. My concern is if its safe to hold grin? I worry that this person or company could have printed a billion grin/laying low for now but attempt a 51% attack in the future. What do you guys think? Am I just being an idiot and worrying too much or is there a risk that i'm adversely affected