It is on the way! Great job. Just make sure someone will be there to receive it when it arrives. The last thing you want is to piss off the gallery by having the installation delayed three days while you try to get your art back from some holding facility.
Just do yourself a favour and send them an email; that way, they know it is coming and if shit hits the fan in whatever form, you have your ass covered with a paper trail. Everyone in the arts hates paperwork and emails (it is why we tried not to get real jobs and ended up in the arts), but seriously, send the email. It is annoying to chase down the artist or gallery and sit there with a van full of art while everyone is frantically calling Uber to get to the gallery.