cigar-shaped, no sound, sub-sonic vibration

I make this report from a story my mother told me.  The date, year, and time are approximate.  
When she was a young girl, her family lived near Baron Fork Creek east of Proctor, Oklahoma.  Around sunset, her father told her to go and fetch the milk cow.  
She headed toward a wind-break of trees.  Up from behind the row of trees rose a shiny silver, cigar-shaped ship.  There was no sound.  However, she could feel a vibration in her throat and lungs (may indicate a low, sub-sonic vibration).  
In the blink of an eye, the ship zipped sideways and disappeared out of sight.  
She fetched the cow home and never said a word about the incident to her family.  I asked her why.  She said her parents wouldn't have believed her and she didn't want to be laughed at by her brothers.
Witness indicates that date of the sighting is approximate.  PD