Yes. This not only with my MBA though... MBP also kicks in the fans when the notebook is used like that. I think, though, it is only to be expected.
The way that the fan aeration angle is designed will mean that when the notebook is on a soft surface, it will dip it a little bit, causing the angle to be obstructed so the fan(s) will kick in to provide same amount of air with higher rps.
Apple does not recommend that the notebook is used on soft surfaces such as bed, sofa, pillow etc. But I sometimes do...
On the same note, this almost the only time I actually hear the fans...
Ah just remembered... You can always use some flat hard surface to elevate the notebook... a thin plastic chopping board, or a sheet of glass... or something else... to that effect... Probably there are some other ways... Come to think of it.. might buy some chopping boards, repackage and sell them as "MacBedMate v.0.1" 10 times the price
EDIT: Apologies for repeating the previous posts... Given I type with two fingers

it takes some time to write an answer... When I started, there was no other posts
