USDT crashed to $0.85 this morning and has since recovered to $0.93. This illustrates concerns that USDT is not as safe a haven as it is intended to be. Even if price becomes stable at 1 USD again I would advise against using USDT in favour of TUSD or another alternative stablecoin.
It is still a real possibility that Tether/Bitfinex are engaging in foul play. We'll see if anything comes of this.