Is $28,300 to build a deck a fair price?

I am choosing between two contractors for a deck project. Contractor A is a specialized deck-building company, and Contractor B is primarily a painter but also a general contractor. I initially received a quote of $32,000 from A and $31,000 from B. I negotiated with B down to $28,500 and made a verbal commitment. Immediately after, A called back offering $28,300. I declined A's lower offer due to my verbal commitment with B, even though I trust A more. I am now concerned about B's licensing and insurance, and whether the contract stipulation for permit and inspection is a sufficient guarantee. I am considering if I should go with A if B is not licensed/insured. The design and materials for the deck are the same for both quotes, and B has a slightly better timeline.