Hi Emma
if you havent had problems before i think they are probably picking at the nails and not telling you the truth. Ask them to come by as soon as they can so you can repair, then have a good look them for any signs of biting e.t.c. if i find picking signs i jokingly say oh you are as bad as me, i tend to pick at mine when im stressed and they usually admit.
Give a good prep and repair while sayingnow these should be grand, also check length as they could be typing more than usual which normally causes problems.
but remember its just a few clients so you cant be bad at doing nails, plus the swift repairs should stop anyone from giving you a bad reputation.
Good luck xx