Cigar shaped object steals 2 hours of two children's time

I was at boarding school in spain in 1968. On or about the date posted a buddy and I climbed a ear by hill to read letters from home ( as we always did). 5 to 10 minutes after reaching the top of the hill my buddy pointed to a solid dull looking cigar shaped object which seem to be carved out of a very clear blue sky. We looked at it for a few seconds before we could comment and we decided itw as not a clound since the edges were crisp and there was some obvious 3 dimentionality to it. The object was just huge since we actually had to move our heads from left to right to see it end to end. Within 15 20 seconds the object seem to be shrinking horizontally in size till it just vanished. To our estimation the whole incident lasted not more than 30 seconds. We ran down to the school to report what we saw and a group of the other children were very exited when they say us we figured that they had also seen the object. To our surprise their exciment was due to the fact that my b! ody and I had been gone for over 2 hours and we had been missed at lunch head count. Fortunelly for us a Franciscan monk in charge of the school was very sympathetic and offered to call a local USA air base (Torrejon) to ask about the phenomenon. The base reported that there had been no scheduled test flights that day but were very interested in a personal report. We declined.
After all this time I still wonder what happened in those 30+ seconds that misteriously turned in over 2 hours of missing time
Date is approximate.  PD