Limited Edition Prints With Tag Line?

Nothing wrong with saying the original work is in the Permanent Collection (if anything is permanent) of the XYZ Museum at wherever the Museum is located. it adds cachè to your work - it doesn't make the museum piece a poster - unless it is one.

What about adding that information to the Certificate of Authenticity, and then affixing it to the back of the print?

And the mona lisa is where and I doubt it's a poster - more like the poster child of Leonardo.

I'd be very careful about afixing anything to the back of a print - perhaps one that went along with the signed and numbered print - but not attached.

I would do it, since I'm happy that I'm in there in the first place, but would ask them to sell my limited print in their souvenir store or at the counter with no comission.
If that doesn't work, I'd try to get something else out of them, like lots of your work displayed for the summer.

Thanks for your helpful comments. I'm very excited about the museums purchase, that's why I was thinking of capitalizing on that. I don't offer prints, but thought this might be an appropriate reason.
Thank you for the great advice!