Dentist said to not worry about attachments falling out. Is he right?

I got my attachments and Invisalign about a week ago and a few days after some of my attachments fell out. I currently have 5 attachments missing. I called my dentist and told him what happened and he said it’s not a big deal and that he will put them back on when I go back in August, 2 months from now. I am worried and confused because online I’m reading the complete opposite of what my dentist told me and I’m paying a lot of money for my treatment.