You're not seeing things. Phil Mickelson does indeed have a logo on his rain gear that is a silhouette version of his jump as he made the putt to win the 2004 Masters, his first major.
While the Mickelson logo might not be in the public consciousness until now, the five-time major winner has actually been using the Mickelson jump silhouette in his golf-course design business and on his personal website for a while now. He just hasn't, until now, put it on his clothing.
After shooting a first-round, 4-under 68 at the 2017 CareerBuilder Challenge, Mickelson declined to elaborate on why he's decided to use the logo now.
According to Golf Channel, Mickelson said the logo is part of a project coming out later in the year and he's not ready to talk about it right now. That could, potentially, reference Mickelson National, a design of his in Calgary, Alberta, Canada. Or it could be for his broader design firm. Or it could be for his golf course ownership business.
But clearly, even if Mickelson won't divulge why he's using his 2004 Masters silhouette logo, it's clear he wants people to know about it.