As a prior HVAC guy, I always hated finding the refrigeration lines mulched over. It meant I had to get dirty to make repairs and when constantly wet, the copper corrodes faster and was harder to clean/braze when leaks developed.
Probably didn't really hurt anything though.
Just make sure you don't mulch above the "floor" of the condenser unit. If rain water can't run out of the condenser, it will rust away in a couple of years. I've seen lots of condensers ruined by mulch piled up around them.