After surgery of any kind, including gum surgery, there will be some swelling.
Don't be alarmed unless the swelling is significant. There also may be slight bruising. Ice packs are a terrific option, do that with crushed ice in a zip-lock bag, cover it with damp washcloth. Hold on area for 20-min, then remove for 20-min, repeat. After 3-days post-op, use moist heat in the same fashion.