Earning that contract was a dream come true for Mayhew, who entered training camp with a legitimate chance to make the big roster.
While he didn't at first, he simply forced his way onto it by being too good in Iowa to keep away for long.
"I've [had] a focus on shooting the puck," Mayhew said. "I've had some goals, which is good, but coach keeps saying, 'Shoot the puck and good things will happen.'"
The message from the NHL staff when he was assigned to Iowa at the end of camp was a simple one.
"Don't be pouty, don't be discouraged, just work that much harder," Mayhew said of their directive. He's certainly done that.
Mayhew doesn't have elite size or can't-miss skill. He was never a highly-rated prospect. But the former Ferris State University alternate captain has, what teammates and coaches in Iowa have called, a puck magnet on the blade of his stick.
For one reason or another, Mayhew seemingly always finds ways to put the puck on net.
"Part of that is, being comfortable in traffic," Iowa assistant coach Brett McLean said of Mayhew last May. "A lot of guys, they'll wait for the puck to come out of traffic, they'll wait at their spot, where Gerry, he'll just go right in there. That's a big part of it. He'll find a way to get there, and you think he'll fall down or you think he's lost it and somehow he'll come out of it with the puck on his stick."
Mayhew assisted on a goal in a 2-1 shootout loss in Des Moines on Saturday night, Iowa's first loss of the season following a 3-0-0 start. Mayhew scored Iowa's only shootout goal as well.
After the game, he got the call from Minnesota assistant GM Tom Kurvers, who also serves as Iowa General Manager, saying he was getting a promotion to the big club.
When the news broke of his ascent on Sunday, teammates, friends and family were texting in large numbers.
