Nearly four months into his leadership, the first chinks seem to have started appearing in David Cameron's armour.
I listened to his response to the Budget debate a couple of weeks ago and, while I thought it was totally over the top, I dismissed it as routine politicking until I heard some gossip to the effect that, for all his apparent affability, Cameron has a notoriously short fuse.
Today's ill-considered outburst, branding the UK Independence Party "fruitcakes, loonies and closet racists" shows at best lack of judgement, at worst an inability to control his tongue.
Gavin Ayling cites another example from the leadership campaign when he apparently lost it with David Davis.
I'm all for politicians using colourful language when appropriate, but given that Cameron is basing part of his political strategy on being a sunnier, more uplifting character than Gordon Brown, I think this sort of thing could turn out to be significant.
I suspect Labour will now be monitoring Mr Cameron very closely to see just what presses his buttons.