If you've gone months without any soda, but start drinking a couple glasses a day, would it be considered normal for it to cause gas & bloating?

Drinking carbonated beverages means you are ingesting CO2 gas which often results in burping and occasionally gas. Bloating may be a different problem, but if resolved by expelling that gas, up or down is a sign of retained gas. Swallowed air, excess CO2, or certain foods like beans, onions, garlic and cruciform vegetables (broccoli, cauliflower, Brussels sprouts, cabbage) may cause the bloat.