This is from the story named: Desirée’s Baby by Kate Chopin
When the baby was about three months old, Desiree awoke one day to the conviction that there was something in the air menacing her peace. It was at first too subtle to grasp. It had only been a disquieting suggestion; an air of mystery among the blacks; unexpected visits from far-off neighbors who could hardly account for their coming. Then a strange, an awful change in her husband's manner, which she dared not ask him to explain. When he spoke to her, it was with averted eyes, from which the old love-light seemed to have gone out. He absented himself from home; and when there, avoided her presence and that of her child, without excuse. And the very spirit of Satan seemed suddenly to take hold of him in his dealings with the slaves. Desiree was miserable enough to die.
Dose it mean that At first she just thought that something might have been happened but she was not sure?
I looked it up but I dont get the meaning of "disquieting suggestion." Actually I dont get the meaning of “suggestion" – "suggestion" has several meanings but I dont know which of them to use here.