On some flights Basic passengers are given a waiver to allow check-in not to charge. But if the OP had gone straight off to check-in and said "I want this checked in" (not knowing the ticket was Basic) and had 2 bags plus laptop then a charge would be levied, yes. Had she turned up with 2 bags within the compliant limits and said "Are you looking for volunteers to check in bags on this Saab flight" the answer may have been "Oh yes please" but that's usually a dialogue done at the gate not check-in.