Not unusual for searches - if you search for " a leather bridle and snaffle bit" the engine will ignore the "a" because it is too short, the word "and" is too common so the number of results would be enormous and mostly irrelevant - so the search would just be for leather, bridle, snaffle & bit.
If you specifically want to search for a phrase including these words then put the whole search phrase in inverted commas.
This applies to the vast majority of search engines like Google etc.