A lot of modern cars are prone to this, my neighbour with his Merc had been having troubles for weeks with odd warnings, phantom alarms and the gearbox would even change gear at odd times. The battery showed a decent voltage but he replaced it on my advice and it all the problems have disappeared.

Just because a battery is only a few months or a couple of years old does not mean it is OK, I have seen numerous even good quality batteries fail in scandalous short times. Buy the best with the longest warranty and keep the receipt is the best advice I can give.

Steve