Give it a month with the impact of the Coronavirus settling in, and Trump’s approval numbers will drop. Don’t be surprised when it happens.
How “concerning.”
It really depends.
If the virus is still a problem on election day, it is trouble for him. BUT, if it has been fixed by then he may well get a 9/11 type bounce from solving the problem.
Remember, Bush got to 90+ % approval after 9/11.
If coronavirus escaped from a Chinese bio-warfare lab and we manage to stop it in the US that is a major victory.