Yeah, I agree. The umpires look for any reason to screw Zim over - I wouldn't have been surprised if that had stood because the evidence "wasn't conclusive" or some such rubbish (aka. the umpire thought it must have hit because HM took so long to review).
But obviously that was nowhere near the bat or glove, so good review and HM gets the chance at a 5th hundred.
Hopefully we get to tea unscathed - the ball is bouncing and turning and a 20 minute reprieve will be very handy now.