That's OK, just vacuum the top.
If it's dusty and stinky, it's probably better to wash it using soap and a gentle brush.
Because it will shrink while wet, make sure to keep the top in the up position until it has dried completely. In the future, you won't have to worry about putting it back up ...

Honestly refreshing seeing a discussion where people are sharing positive experiences for once usually threads involving online vehicle purchases end in horror stories