Rear End Instability?

[Timbo2]

Hi, I bought my Boxster in January this year. It's a 2001 986 with 43K miles on the clock. I had a health check done at JMG Porsche Specialists in Christchurch and they found no major problems. As my confidence has grown I've begun to push the car harder and generally it performs and handles very well. however, I recently had a somewhat 'cheek clenching' moment when, whilst changing into top at around 115mph on what I would consider to be a relatively gentle curve, the back end suddenly felt very twitchy. It's difficult to say exactly what was going on but I think that it was beginning to loose traction and understeer. The weather conditions were warm and dry and the road surface was good. I gently backed off to a neutral throttle and it settled down again.

I know that it's difficult to tell from this subjective description, but I would like to find out whether this behaviour can be expected, or if I need to look at tyres/alignment. Tyres are Michelin Pilot's all round with about 4mm left at the rear.

I suppose I'm a bit worried now about the predictability of the cars handling and just how much warning I can expect when reaching the limit. Any comments welcome