For a month or so now I've noticed that Buddy will randomly twitch while I'm holding him or he's just sitting on my lap. It's a full body jerk, like you'd feel when they flinch or have the hiccups, but it happens with no outside stimulus and there is no audible noise like when they hiccup. Is this normal? Or something I should be concerned about? Could he be coughing inaudibly? Could this indicate some sort of neurological issue? He's only about 6-8 months old if that make any difference.