Paint Bubble

I remember a thread from Harvey197 about paint bubbles..

I have just taken my car to get two new front tyres on and have noticed that there is a paint bubble on my back quarter about 30cm from my petrol cap just along the line of the car..

How do i stand with warranty?
 
is it really that long? i was under the impression it was 3? I take it the bubble means the dreaded rust??!!
 
Never knew it was 12 years.

I wouldn't say its exactly a bubble after looking again, its more like a single bit of grit under the paint. I think its mainly due to bad prep before the final coats of paint isn't it?