Colour transfer

I have owned many Radley handbags mostly purchased from outlet centres.
I have been particularly impressed by the exchange policy of up to a year if a fault develops up to a year from purchase.

I have recently had 2 bags transfer colour in either very hot sun of 37 degrees or rain this week and wonder if this is common or a fault.

The dogs tend to fall off quite regularly but overall I like the design of the products.