This is why direct to substrate is a better option. Roots generalyl know up from down, but if flipping it around and handling it etc, it probably got 'confused.' Also, possible it just took path of least resistance.. something blocked it so it tried to go around etc.
maybe, a transplant is enough, but fiddling with it carries its own risks too. Seedlings are a bit picky about being fucked with and somtimes just stop growing when you do mess with them. Damaging the root is incredibly easy at this point. IF no fine hairs branching off and can easily seperate from the peat puck, maybe wise to re-plant and ensure the tap root isn't tangled at the top.
if you simply transplant and make sure the bury the exposed tap root, it should turn downward on its own, but it'll still be quite superficial at that bend. Any compaction or erosion and it gets exposed will simply turn exposed surface into stem eventually. Usually not too big of a problem, but the 'tap root' is not just some small stretch of exposed root. I don't know what kind of ramifications of a seedling haveing to develop a new tap root is, if that becomes necessary.. i'd assume it is at least a bit of delay.
This is why it's good to plant twice as many seeds as you need. Fuck the headaches, lol. cast them off and keep the good ones rolling.