No Warrent to search a house...?

I just found out today that my husband was arrested...the crime he did was so unlike him...this is so horrible...when the cops came by they didnt ask to search my house but I offered. They found a pipe in my husbands drawer. They didnt really check the whole house and told me i needed to search my house and if i found anything else to let them know. They said If anything was to be found in my house if they had to come back that it would be on me. I have searched and found nothing...I am concerned though, because I cant be sure that I have looked everywhere..I dont think like an addict. If they come back would this really be put on me...or could he take blame..I just dont see the fairness when a wife has no idea the drugs are in her house, has never broken the law or done drugs herself, why should anything be on someone who knows nothing about this? Can someone explain the laws to me?