MGTF once off overheating

Looking for some advice please. I just bought an 04 115 MGTF as i fancied a convertible for the summer. Seeing the prices of the TF i thought why not. Anyway i bought the car after checking the usual stuff and all was well. Then the temp gauge started rising on the way home. At this point i'm in slow moving roadworks traffic with no hard shoulder. So i carry on as gentle as i could with my eyes glued to the temp gauge. As soon as the gauge hit red i heard a small pop noise then the gauge drops back down to normal!! I pull over at the next service station and let it cool down. The header tank is empty so i fill it and leave the cap off, then nurse it home (40 miles). To my surprise it didnt use a drop, the oil is clean. Proper inspection shows no contamination, constant normal temperature with no water usage and the engine pulls as it should.


Am i being overly cautious because of the K-series HGF stories or do i have a genuine problem? I cant get the problem to re-occur. I'm currently driving about with bottles of water in the boot but so far (another 50 miles or so) i havent topped up at all.

Any advice would be appreciated.

Thanks
Mini1380cc

Thanks guys. I'll bleed it again properly this time. Still so far so good.