Hi,
My DD who is nearly 2 has just started doing this too,it happened after we got back from a long weekend break,where she was a little unsettled at bedtime..strange place,not her cot etc..she took 10 mins to fall asleep after crying.when we got back home,she started crying when I put her down for her nap,and at bedtime too,only for literally 30 seconds to a minute,then she falls asleep.I think it is a bit of separation anxiety taking place again,she doesn't want mum to leave!.She doesn't do it with my husband,when he puts her down for her nap,so guess this is probably the case.My friend went through the same thing,with her DD at this age too,she was told,it is a typical thing that toddlers do at this age,resistance to sleep.I've had to cut Lilys nap down,and move it later,as she was taking 1/2 hr or so to fall asleep at night,she now falls asleep within minutes again,and is waking later,so hopefully thats worked.There's always some sort of challenge isn't there to keep us on our toes! Hope this helps!
Clare x