This game is close for me but if I had to pick I would take GB too.
You should have waited a little while. The spread has moved to 3 1/2 and will likely hit 4 by game time.
Just a word of advice, unless an early line jumps out at you and you think that the odds will not get any better, it is best to wait as close to game time as you can before laying a bet. Injuries will affect the lines a lot.
Also watch out for "hot games" ones where you know that the lines will move. If the Chargers are playing against the Redskins I will probably wait as close to gametime as possible before betting on the Chargers. The 'Skins are popular and people betting on the Skins during the week will probably make the odds on the Chargers better later on during the week. But the reverse is also true - if the Skins have good odds early in the week I will bet on the Skins as early as possible knowing that other people will be betting the skins as well and the odds will get worse for me.
"I think that gay marriage should be something between a man and a woman" Governor Arnold Schwarzenegger