Mont. Code Ann. § 77-3-441

In all cases where an oil and gas lease issued after March 3, 1955, is surrendered for cancellation before its expiration, relinquished to the state, or canceled through proceedings on the part of the state, no new lease on the lands under such lease may be issued within 30 days from the date of cancellation or relinquishing. This restriction does not apply, however, in cases of bona fide assignment.