Mich. Comp. Laws § 129.210

Sec. 10. This act shall not apply to any contract awarded pursuant to an invitation for bids issued on or before the effective date hereof, or to any person or bonds in respect to any such contract. The rights, duties, and obligations of parties arising under, or incidental to, bonds executed prior to the effective date of this act shall continue to be governed by the statutes heretofore applicable to such bonds.