UPDATE - 7/15@11:34AM: The Foos played a second show in Toronto the following night and paid tribute to Rush once again by covering a few snippets of some Rush tunes as seen in this video (thanks John G).

UPDATE - 7/9@8:26PM: This story caused quite a buzz in the online music press, getting picked up by Billboard, the Toronto Star, Q107, Music Times and Alternative Nation to name a few.

The Foo Fighters' have been occasionally covering Rush's Tom Sawyer as part of their Sonic Highways Tour tour over the past several months. Last night they played the Molson Canadian Amphitheater in Toronto and not surprisingly covered the song once again. Just before the song drummer Taylor Hawkins made a comment about all the Rush t-shirts he saw in the audience. Dave Grohl then chimed in saying, "that's great because we have 2 special guests". The crowd then went crazy thinking that maybe Geddy Lee and Alex Lifeson would come out and make a guest appearance like they did at a Foos show in Toronto back in 2008. But it turned out the special guests were Grohl's mom and Geddy Lee's mom. Once they broke into Tom Sawyer, they would occasionally show a shot of the 2 moms up on the big screen as seen in this video (thanks to William M for the video and the info). Rush also posted a photo of the 2 moms to their Facebook page just a short time ago with a message from Geddy:

Thanks Foo Fighters & Dave's Mom for making my mom's night at your concert ..surreal! She loves u guys forever for playing Tom Sawyer ;)
- Geddy