THEME:   none, but four triples   
GOOD ONES:     Pitcher of milk?   ELSIE [a cow used sell Borden products --- at least 70 years ago!]   
Fall preceder   TRIP   
Letters from Greece   ZETAS   
Letters from Lancaster   ZEDS   
Chest protectors   BIBS   
Sign of possession   APOSTROPHE [not requiring an exorcism]      
BTW:   With it   HEP [actually the clue needs "once" otherwise it shows the opposite]      
Pass a second time in a race   
RELAP [I am familiar with LAP as a verb but RELAP is doubtful]      
Festival d'___ de Quebec: annual music event   ETE [Finally an acceptable clue for this Xword staple!    Of course, I never heard of it but I'm so glad it exists and Barry cared enough to find it.]      
I prefer themes, but this one was both clever and challenging.
RATING:    
 
 
Three grins = Loved it; Two grins = Enjoyed it; One grin = A bit bland for my taste; One teardrop = Not much fun