If this occurs during a daily draw, I use whatever card(s) fall out of the deck as the message for the day. I do not see the occurrence as a result of clumsiness but as Divinerguy: the deck or ThePowersThatBe speaking. Every card or cards resulting from such has had significance, sometimes startling.
Whether for a personal throw or for someone else, I stop shuffling & use the card as the first card of the throw. I then deal the cards from the top of the deck for the rest of the throw. If there are more than one, I use them as the initial throw.
SquigglyWiggly's comment reminds me of the most unusual experience several years ago. I was shuffling my RSW deck at the foot of my bed for the daily draw when a small pile of cards flew over my left shoulder & fell in slow motion behind me, giving me the opportunity to watch them as they fell. Whilst I was stunned, I was able to observe the order in which they fell. I counted 9 cards--one short of a Celtic Spread. I took that to mean a reading. I wrote the cards in my journal but did not get to look at them closely until after work. The first card was Knight-Cups. Immediately, I saw that as representing a relative who was incarcerated. The rest described his experiences & also represented a warning. Due to what I understood from them, I told another relative whom he kept in touch with of the concerns as I saw them. I also wrote to him. Recommended that he be careful, especially in the evenings when it seemed there were more incidents with tempers flaring & the possibility of violence. That he needed to keep to himself as much as was practical, to remain alert & to be careful of his mouth.
Subsequently, he phoned me collect (the only way inmates are able to use the phone). In the evenings was when the inmates had some free time to watch the telly in a common room. There had been recent incidents involving arguments over what program to watch. They often led to fights with serious injuries. He assured me he was staying out of trouble & had attained a trustee status where he had a wee more freedom than the majority. He'd also developed major dental problems that required medical attention due to abcessed teeth.