in our experince, my dd wasn't ready to lose the catnap until 9 months. but yours may be different. does she seem not tired or just doesn't want to be put down? if she seems not tired, maybe you can try increasing the awake time a bit.
around 6 or 7 months, my dd, who always goes down well for naps, started doing the same thing as yours. when it was nap time, out of the blue, even though she was tired, she would cling to me and scream if i put her down. i really think this was separation anxiety. it also disrupted night sleep a bit at the same time. i think it was sep. anx. because she did not do this when dh put her down. have you tried letting someone else put her for a nap and see what happens? what i did to help my dd was give her an extra long wind down (lots of one on one attention right before nap) and then try to lay her down. i let her cry a bit, sometimes she would settle. other times, when the crying got intense or went on too long, i would rock her. bad, i know!! but it got us throught that time. she did it for about a week and hasn't done it since.
i am sure your vacation has her thrown a little.
