Store doing repairs without asking?

Brought my bike in for the free level 1 service within the first year. Now the store did repairs for $108 on top of that. Employees seemed professional and I definitely dont mean to allege they ripped me off.

That said, it strikes me as somewhat strange that they wouldnt inform me beforehand of the necessity of these repairs and of the costs involved and ask for my consent? Just wondering, is this a normal practice?