My DD was 5 when she went under a ga, so older, but she also had a reaction to it.
She had gas, not sure if she'd have had the tube since they did tonsils & adenoids as well as grommits, but if a canula is needed, most will do it while they are under.
Just wanted to drop in & say be prepared. Most kids are fine, but some will react differently after. DD wasn't sleepy at all & came out of the OR awake & very juttery & freaked out.
I just wanted to warn you & let you know that it is ok. Be strong, coz it can be scary (I failed I they had to tell me to get a grip before I went in), but she will be fine.
I'm sure your DD will be perfect The going under can be scary too. A friend's DS went under a bit younger than your DD & she said when he went to sleep it was scary how limp he went.
I know its not the nicest post, but just a warning, just so you can be prepared.
Good luck