RR,
I can only assume you are talking about Ryanair. There is a temporary company restriction in place issued by the Chief Pilot that we must ensure a Buffet manoeuvre margin of at least 1.5G which is in contrast to our previous of (I think) 1.3G, due to occurences in flight which are still under investigation we are told. This results in cruise levels of as low as 330 when we are heavier.