I wouldn't worry about it. I had an instance whilst doing a few short trips that the car was trying to do a regen, it hadn't got as far as the light coming on but every time I stopped I could hear the fan running on and the start stop had stopped working, i admit I was becoming a little paranoid. After a long caravan towing session this cleared and I have had no issues since. A postman lives over the road, recently he was sat outside his house revving the engine of his van. Curiosity got the better of me and I asked what the problem was, he explained the car was just doing a regen and he was running the engine at slightly elevated revs. He said he had to do this until the light went off, otherwise the car would pack up, it happened about twice a week. Since then, as my experiences pale into insignificance compared to a postmans van I have stopped worrying about regens, although I do use the car approx once a month for towing which is perfect for clearing DPF's. The moral of the story is, no light - no worries.