Did you know that Mike Glennon has a brother? Did you know that older bro Sean Glennon has a Twitter account? Did you know that he uses it to take shots at Lovie Smith?
JoeBucsFan first grabbed that tweet, and Gil Arcia apparently screen-capped the Tweet, although it should be noted that it's just a screen-cap. I didn't see the Tweet myself.
If that's genuine, that's...amusing. It also has to be somewhat frustrating for Mike Glennon because no matter what happened behind closed doors, this is not helping him. You have to be smarter than that, Sean! See also, Marcus Vick.
The easiest explanation is that he saw Lovie Smith's press conference remarks that Mike Glennon's job isn't secure anymore. A perfectly reasonable stance given Glennon's struggles in recent weeks, but one that routinely annoys family members and close friends. It's never fun when someone you're close to struggles at work, and it's always easy to blame other people. Ref: Gisele Bundchen.
There's one exceedingly simple way for Mike Glennon to convince Lovie Smith not to bench him: play and practice better. Because the last few weeks have not been good enough.