First of all it seems unlikely for the card to be found by anyone in the first place , after all it is a tiny card, besides this people usually do not have that much time to make efforts to explore an abandoned little object which by all means would appear to be a waste product anyways if at all found in the first place.
So your thoughts clouding your mind at the moment are bordering on remote and rarest of rare possibilities and case scenarios which unnecessary lead to distress and unrest in your mind. You got to get over this as there are more chances of the card going unnoticed and possibly destroyed than anyone finding it and then having the energy and time to explore it to find out the data it holds.
Also I must address here that everyone has a private life which one keeps to himself/ herself and within the realms of private / personal life there are some moments which are intimate, not to be shared with others , however if in a rarest of rare case these private moments get revealed to the outside world then it is not going to change people's perception about that person , this I tell you because in your case too if at all you had some private content stored in the card and if we consider it an out and out rarest of rare case that someone finds it and has the time, energy and enthusiasm to explore it , even then I feel it will not amount to any sort of embarrassment for you , since you command a good reputation which is not going to get tarnished by such a small incident which can happen with anyone.
However this is rarest of rare case if at all it occurs in the first place.
You see people are too busy in their own lives to notice such a small card and take pains to explore it, so relax and ease your mind and just go on the trip with your friends and enjoy yourself without giving much importance to this incident.
It is anyways more likely for you to find it later just like that than anyone else , so please stop worrying and carry on with your life as usual.
I hope this helps.
Wish you all the best.
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