New Suspension Seals Cracked - neglect or poor quality parts? 1957 Buick

[Angelfish]

Two years ago I had to move my disassembled 57 Buick to a new house so I slapped the front suspension together to facilitate the move.  The car sat unmoved for a year in which time all the new seals in the A-arms cracked.  The ball joint boots are still ok. 

 

I bought the seals from a well known supplier of parts for this car.  I have the suspension back apart and need to replace all the seals in the A-arm assemblies, but I'd like to know that they will hold up for a while.

 

Was is just the car sitting or do I need to look elsewhere for seals?  I can't imagine there's a lot of different companies making them.